This patient has a partial D phenotype, not a true weak D phenotype, based on the following:
- Her RBCs reacted weakly with some anti-D reagents but strongly with others, indicating a qualitative antigenic variation (partial D) rather than purely quantitative variation (weak D).
- She produced alloanti-D, which is uncommon for true weak D phenotypes since all D epitopes are present, even at low levels. Production of alloanti-D suggests one or more epitopes are missing (partial D).
- DNA analysis predicted amino acid changes in the external portion of RhD, not just the internal/transmembrane regions as is typical for true weak D. External changes are more likely to result in a
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The weak D phenotype is thought to arise from several mechanisms. .pdfmckenziecast21211
The weak D phenotype is thought to arise from several mechanisms. Which one of the following
statements is false?
C gene is in trans position to D gene, this results in a weakening influence on the D gene,
examples CDe/Cde and cDe/Cde.
Weak D antigen is genetically transmitted. This can occur rarely in R1 and R2 genotypes in
caucasians. Also occurs in the Ro genotype in certain racial groups more commonly.
The D antigen consists of multiple pieces (is a mosaic). Occasionally one or more of these pieces
is missing. The red cells are said to have a partial D.
D deletion genes gives rise to weakened expression of D antigen.
Rh null cells lack:
MNSs antigens.
Lewis antigens.
Normal oxygen-carrying capacity.
Rh antigens.
There are two closely related and closely linked genes.
Enzyme techniques, in conjunction with an IgM anti-D.
Increasing the time for the incubation of the saline phase.
Performance of an IAT using an IgG anti-D.
Don\'t need to do it in a blood bank.
C gene is in trans position to D gene, this results in a weakening influence on the D gene,
examples CDe/Cde and cDe/Cde.
Weak D antigen is genetically transmitted. This can occur rarely in R1 and R2 genotypes in
caucasians. Also occurs in the Ro genotype in certain racial groups more commonly.
The D antigen consists of multiple pieces (is a mosaic). Occasionally one or more of these
pieces is missing. The red cells are said to have a partial D.
D deletion genes gives rise to weakened expression of D antigen.
Solution
The weak D phenotype is thought to arise from several mechanisms. Which one of the following
statements is false?
D deletion genes gives rise to weakened expression of D antigen.
Rh null cells lack:
Rh antigens.
There are two closely related and closely linked genes.
Enzyme techniques, in conjunction with an IgM anti-D.
Increasing the time for the incubation of the saline phase.
Performance of an IAT using an IgG anti-D.
Don\'t need to do it in a blood bank.
Last one is an incomplete question
D deletion genes gives rise to weakened expression of D antigen..
Concurrent Determination of ABO RhD Blood Types and the HIV-1 Resistance Mark...Thermo Fisher Scientific
For optimal outcomes when matching bone marrow donors with their recipients, it is preferable to use bone marrow of identical or compatible blood types. Bone marrow registries thus require high resolution HLA genotyping data to match donor specimens with their recipients. We developed a research assay to aid in these investigations, which utilizes buccal swab DNA from potential donors to determine the ABO and Rh-antigen genotypes. In addition, the assay detects a 32 bp deletion in the CCR5 gene. Homozygous carriers of this deletion are resistant to HIV-1 infection, and thus could be valuable stem cell donors for HIV-infected recipients
Rh typing and its technique , BLOOD TYPING , Rhesus (Rh) typing , procedures of rh typing, process of Rh typing, Test limitations, Sources of Error in Rh Antigen Typing, False positive reactions' reason, False negative reactions' reasons
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
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Session 1 - Clinical Significance of RhD
1. The Myth and Mystery of RhD
Quotient Biodiagnostics Industry Workshop
October 24, 2011
Christine Lomas-Francis MSc, FIBMS
Technical Director
Immunohematology and Genomics
New York Blood Center
1
2. The Importance of RhD Typing
• The RhD antigen is the most
immunogenic of the Rh antigens
• Second only to ABO in clinical
significance
• Determine the RhD type of patients and
donors to prevent sensitization to RhD
and thus transfusion reactions and
hemolytic disease of the fetus and
newborn (HDFN) due to anti-D
2
3. Establishing the “correct” D Type
• Fundamental to safe transfusion practice
• Potent monoclonal anti-D are used and yet………….
• Interpretation of the D type of some patients and
donors is a challenge because some people have:
– qualitative variation in D antigen expression, referred
to as partial D
– quantitative reduction in D antigen expression,
referred to as weak D
• Careful reagent selection, an understanding of the
reagent characteristics and of the nature of the D
antigen is valuable when interpreting D typing
3
4. Objectives
• Discuss D antigen expression
• Review weak and partial D phenotypes
• Review the regulatory requirements and
reagent use when typing patients and
donors for D
• Explain the clinical relevance of
distinguishing between weak and partial
D phenotypes in patient and donor
testing
4
5. RHD and RHCE encode RhD and RhCE proteins
Genes RHCE
RHD
Rh positive 5’ 3’ 3’ ce, Ce, cE, or CE 5’
D antigen Cc and Ee antigens
Proteins C/c E/e
Ser103Pro Pro226Ala
RhD RhCE
RhD and RhCE differ by 32 to 35 amino acids
Adapted from: Westhoff CM., Semin.Hematol. 2007;44:42-50
5
6. RHD and RHCE encode RhD and RhCE proteins
Genes RHCE
RHD
Rh positive 5’ 3’ 3’ ce, Ce, cE, or CE 5’
D antigen Cc and Ee antigens
D epitopes
Proteins
C/c E/e
Ser103Pro Pro226Ala
RhD RhCE
RhD and RhCE differ by 32 to 35 amino acids
Adapted from: Westhoff CM., Semin.Hematol. 2007;44:42-50
6
7. RhD: D Phenotype and Immunogenicity
Genes RHCE
RHD
Rh positive 5’ 3’ 3’ ce, Ce, cE, or CE 5’
D antigen Cc and Ee antigens
X Deleted X
Rh negative 3’ ce 5’
Protein C/c E/e
Ser103Pro Pro226Ala
No RhD protein
All D epitopes missing RhCE
RHD gene deletion: most common in populations of European ancestry
Adapted from: Westhoff CM., Semin.Hematol. 2007;44:42-50
7
8. D Antigen Expression
RhD D is composed of many epitopes
• Continuum of strength of expression
• “Conventional” D+ (expresses all D epitopes)
• ~ 200 different RHD alleles encode proteins with amino acid
changes that cause variation in antigen expression
• Partial D (D categories, D mosaics); more prevalent in Blacks
• Weak D (formerly DU); 0.2 to 1% of Whites; prevalence can
depend on anti-D reagent
• Del (DEL); lowest antigen density
8
9. Partial D Phenotype: Qualitative Variant of D
Changes predicted to be in
RhD the external loops of RhD
•Discovered as some D+ people made alloanti-D or because
RBCs reacted with some but not all anti-D
•Most partial D due to hybrid genes: parts of RHD replaced by
parts of RHCE; some are due to single nucleotide changes
•RhD protein with missing D epitopes
•RBCs may type as D-positive, but reagent dependant
•Alloanti-D can be made against missing epitopes
•Some partial D express novel low prevalence antigens: eg.
Goa on DIVa; DW on DVa; Tar on DVII
9
10. Partial D Phenotypes
• Originally serologically divided into
categories DII to DVII (based on reaction
with anti-D made by D+ people)
• Later by use of monoclonal anti-D
• Further sub-division of categories by
molecular studies: e.g. 6 types of DIV and 4
types of DVI
• ~ 80 alleles that encode partial D; not all can
be serologically distinguished
• Usually given names; often 3 or 4 letters
such as DBT, DAR, DNB, DHAR….
10
11. Weak D Phenotype: Quantitative Variant of D
G385A
Type 2
RhD Changes predicted to be in
the transmembrane or
S3C
Type 3 V270G
cytoplasmic regions
Type 1
•Reduced amount of D
•All D epitopes present but weakly expressed
•May require indirect antiglobulin test (IAT) for detection
•Not (usually) associated with alloanti-D production
•Now 80+ different weak D types (Types -1,-2,-3 = ~ 90%)
11
12. Weak D Phenotypes
• Weak D phenotypes given numbers
– Weak D type 1, type 2, type 3……up to 76 with
some sub-types (4.1, 4.2 etc)
• Weak D classification is tricky
– Can be reagent and method dependent
– Sample can be 2+ in tube at IS, stronger in gel and
negative in solid phase
– Very ‘fluid’ statistics for prevalence of weak D
based on serology
• Weak D types usually cannot be distinguished
serologically; requires DNA analysis
12
13. The Del (DEL) Phenotype
•RBCs type as D negative (including at IAT)
•RBCs express very low level of D antigen (20
antigen sites/RBC); reduced amount of RhD
protein in membrane
•Detected only by adsorption and elution
•Del most often found in Asian populations (10
to 30% of D– Asians; 0.027% in European D– )
•Most Del RBCs express C, a few express E
•More than 20 molecular bases
13
14. D and D-like Epitopes Expressed on RhCE
1 2 3 4 5 6 7 8 9 10
RHce*CF
VS+, Crawford+
W16C Q233E L245V
Flegel et al. The RHCE allele ceCF: the molecular basis of Crawford (RH43). Transfusion, 2006; 46:1334-1342
RHD*DHAR
Rh33+, FPTT+
•Several Rhce proteins have a few D-specific amino acids
•Yet they react (strongly) with some anti-D reagents
•Patient typed D at one hospital, D+ at another, different reagents used for
typing, transfused D+ RBCs and made anti-D
Patient returned as a donor; caused donor D typing discrepancy
•DHar found in people with German ancestry
•Crawford phenotype found in people with African ancestry
•Also ceRT and ceSL variants; more likely to be an issue in Europe
because of cell lines in reagents
14
15. Partial D and Weak D: Comparison
All epitopes Make anti-D Patient Location of
present considered changes
Partial D No Yes D– External
Weak D Yes No D+ Internal
In a clinical setting all we need to do is to determine if
the patient is D+, or has a partial or weak D phenotype!
We’ll come to donors later…………..
15
16. Case Study
Patient: D typing results indicate her
African American RBCs are D+ with (slightly)
Delivered her 3rd baby weakened expression
Anti-D, 3+ by PEG IAT in her RBCs also C E c+ e+
plasma at delivery
Autocontrol negative
Results obtained in direct testing
Anti-D reagents Reaction with DNA analysis predicts:
IgM + IgG Patient RBCs Presence of weak D type 4
#1 2+ Associated with 2 amino acid
#2 3+
changes: T201R and F223V
that are predicted to be in the
#3 3+ internal portion of RhD
#4 2+
16
17. What is a True Weak D Phenotype?
Comment added to patient report:
“This patient has a RHD allele first reported to encode a weak D
but now known to encode a partial D phenotype associated with
the production of alloanti-D.”
This should be considered a weak partial D phenotype
All epitopes Make anti-D Patient Location of
present considered changes
Weak D Yes/no No/yes/don’t D+?? Internal
know
In real life it’s a different story!
Some weak D types do make alloanti-D, e.g.:
Weak D type 4.0, 4.2, 11, 15, 33
Yet changes in the RhD protein appear to be internal
Does the terminology add to our confusion?
17
18. Prevalence of Phenotypes with Altered D
• Limited statistics; more studies in last few years at DNA level
• Overall ~ 2% of people express altered D
• ~ 1% of Europeans express a weak D phenotype
• DVI most “common” partial D in Caucasian populations
– 0.02% to 0.05% in Caucasians (~ 0.02% in Germany; 0.04% in UK;
2.9% in Palestinians)
• DNB also “common”; highest in Swiss (1 in 292)
• Partial D phenotype more “common” in populations of African
ancestry, especially DIII and DAR
DVII: 1 in 900 DAR: 5 in 100 in DV: 1 in 30,000
S Africa
DFR: 1 in 60,000 DIIIa: 4 in 100 in Weak D type 15: 1
African Americans in 15,000
DHar: 1 in 60,000 DIV: 1 in 10,000
18
19. RhD Variants in Multiethnic Prenatal Population
• Recent study** from Boston University Medical Center
• Screened 501 patients with 4 anti-D (2 in tubes, 2 in
solid phase) and referred discrepant results for DNA
analysis
• 11 discrepancies (2.2%)
– One tube reagent reacted with all 11 samples (1+ to 3+)
– Another tube reagent reacted with 7 of 11 samples (1+ to 2+)
– Solid phase: 4 of 11 reacted with one reagent (1+ to 4+); 2 of
11 reacted with another reagent (3+)
• DNA analysis found: weak D type 4 (n=4); weak D type
3 (n=1); DAR (n=3); DV (n=2); unknown (1)
**Wand D, et al. Am J Clin Pathol; 2010: 134: 438-442
19
20. Monoclonal Anti-D Reagents: Background
• Potent and specific; because they are monoclonal each clone
recognizes a single D epitope
• Antibody to single epitope does not react with all partial (and weak) D
therefore “blended” reagents:
– Blend of monoclonal (IgM) and polyclonal (IgG) antibodies
– Blend of two or more monoclonal antibodies, each from a different cell line:
IgG or IgM, or a combination of IgG + IgM
– Limited number of stable IgM-secreting cell lines available
• Clones for anti-D reagents selected based on:
– Detection, or not, of partial DVI, most prevalent partial D in Caucasians
– DVI strategy: D-positive as donors; D-negative as recipients/RhIG candidates
– -IgM antibody does not react with DVI – (Initial Spin=negative)
– -IgG antibody reacts with DVI in weak D test = positive
• Similar criteria in USA and Europe
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21. D Typing and Result Interpretation can be Problematic!
Different anti-D reagents:
– Contain different clones
– Can react differently with weak or partial D
phenotypes
– FDA: only reactivity with DIV, DVa, & DVI need be
specified
• Multiple methods:
– Hospitals: tube tests, gel, solid phase, may or may
not proceed to AHG test for weak D
– Donor centers: automated analyzers, tube tests
• Variability in expression of D
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23. Regulatory Aspects: Donors
USA UK (Europe)
UK BTS Guidelines for the Blood
AABB Standards, 27th ed
Transfusion Services
5.8.2 Determination of Rh Type
for All Collections • The D blood group must be determined
on each donation of blood.
The Rh type shall be
determined for each • … for first time donors use two anti-D
collection with anti-D blood grouping reagents, capable of
reagent. If the initial test with detecting between them DIV, DV and
anti-D is negative, the blood DVI. If two monoclonal anti-Ds are used,
shall be tested using a they should be from different clones.
method designed to detect • If the results … are discordant or
weak D. equivocal, the tests should be repeated.
When either test is positive, Where the D group is in doubt it is safer
the label shall read “Rh to classify such donors as D positive.
POSITIVE” • For known (repeat) donors one anti-D
reagent, or blended reagent, that detects
weak D, DIV, DV and DVI can be used.
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24. Regulatory Aspects: Patients
USA UK (Europe)
UK BTS Guidelines for the Blood
AABB Standards, 27th ed. Transfusion Services
5.13.2 Rh Type • Patients should not be classified
The Rh type shall be as D positive on the basis of a
determined with anti-D weak reaction with a single anti-
reagent. The test for weak D reagent. If clear positive
D is unnecessary when results are not obtained with
testing the patient. two monoclonal anti-D reagents
it is safer to classify the patient
as D negative.
• Reagents used for D grouping
patients should not detect
category DVI.
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25. UK Guidelines for Patient Testing
More detailed than those in the USA
Weak D and Partial D
• …” reagents vary widely in their ability to detect both partial D
and weak D”
• …” when two different reagents are used it is helpful to use
those of a similar reactivity with partial D and weak D red cells,
to reduce the number of discrepancies”
• …” if a discrepancy occurs the patient should be treated as D
negative until the D status is resolved”
• ….”patients should not be classified as D positive on the basis
of a weak reaction with a single anti-D reagent. If clear positive
results are not obtained with two monoclonal anti-D reagents
it is safer to classify the patient as D negative”
• …”It is useful when investigating patients with suspected
weak D or partial D to test the patients' cells against an
identification kit containing monoclonal antibodies directed
against the different epitopes of the D antigen”
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26. Defining Weak D and Partial D status
Is it clinically useful?
• Patient setting:
– Carriers of partial D and some “weak D” phenotypes can be
immunized to make anti-D by transfusion and pregnancy;
detect those at risk and make informed decision
– Avoid transfusion of D+ blood and provide Rh immune
globulin
– Ideal method for identification? Requires special reagents
(monoclonal anti-D kits) and/or DNA analysis to do so
– Carriers of true weak D phenotypes cannot be immunized to
make anti-D
• D+ blood can be transfused
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27. Give RhIG to Women with Weak or Discrepant D types?
• No definitive answer; range of expert opinions
• Flegel et al: if reactions with anti-D at immediate
spin are less then 2+ consider as D– and give RhIG;
if DNA analysis performed, weak D type 1, 2, 3, 4.0,
4.1 do not need RhIG
• Noizat-Pirenne et al: weak D type 1, 2, 3 do not need
RhIG; but beware of weak D in Dce haplotype as
this is often a partial D
• Excellent summary of current dilemma in:
Questions & Answers; AABB News (April 2011) Vol
13 # 4: page 6 (Glenn Ramsey, MD)
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28. Strategies for D testing
Donors
• Goal: label donor RBCs with any amount of
D as “Rh positive”
• Potential Problem: Weak D; some are
missed; even with IAT testing :
– those with low antigen expression (type 2, 5, 9,
10,12,15,17,18)
– Del; all are typed as D negative (prevalent in
Asians)
• Less immunogenic, but appear to be able to
stimulate anti-D in D– patients; weak D types
1, 2, 26, Del , have stimulated anti-D
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29. Strategies for D testing (cont’d)
Donor:
• Select reagents to detect as many D
variants as possible
• Test for weak D
• Understand the differences in the
reagents and know how to manage
“conflicts”
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30. Important!
• Be aware of the ethnicity of the patient and
donor population being tested
• Prevalence of the various partial and weak D
phenotypes is not the same in all ethnic
groups
• Be familiar with the reaction profile of the
anti-D clones used in a particular reagent
• Be aware that formulation of a reagent can
affect the reactivity of a monoclonal anti-D
• Accept that a small number of samples will
be challenging to classify
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