DBA is a fascinating and complex erythroid disorder, as illustrated from the study of the DBA family we described. Progress is being made in our understanding of the molecular basis for DBA, pathophysiology of the disease, and developing and pursuing new therapeutic options. In this review we studied that these advances will enable better clinical management of the patients with DBA in the coming years. DBA diagnosis requires a correlation between examination findings and laboratory abnormalities demonstrating macrocytic anemia, elevated hemoglobin F levels, high erythrocyte deaminase activity, and confirmation with bone marrow biopsy and gene karyotyping.

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Diamond Blackfan Anaemia (DBA)
By Preeti (B. Pharm 8th sem)
Roll no. 18BPD1522

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INTRODUCTION
Diamond Blackfan anemia (DBA) is a rare congenital hypoplastic anemia that usually
presents with progressive pallor in infancy.
DBA is characterised by aplasia of RBC's as well as skeletal deformities & low
stature,often occur soon after birth.
Growth retardation & congenital deformities of the head, heart, neck, upper limbs, &
urinary system are found in 30-50 % of DBA patients.
WBC count is normal or slightly lower, whereas the platelet count is slightly higher.
Majority of patients show raised MCV(Mean corpuscular volume), enhanced eADA
(erythrocyte adenosine deaminase activity) & elevated foetal haemoglobin.

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EPIDEMIOLOGY
DBA was initially identified by Joseph in 1936.
Then, Diamond & Blackfan reported it two years later.
The first DBA gene, RPS19, was discovered to be mutated in 25% of probands
with both sporadic & familial DBA.
It has been estimated that 5-7 cases of DBA occur per million live births.
With a diagnosis age of 12 weeks, the average age of presentation is 8 weeks.
There have been reported cases of foetal hydrops ( severe swelling (edema) in
an unborn baby or a newborn baby which is life threatening) also.

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EPIDEMIOLOGY
A descriptive observational retrospective cohort study was carried out by The
Children's Hospital and The Institute of Child Health Lahore using the medical
records of kids who were diagnosed with DBA between January 2008 and
December 2017. (10 years)
A total of 74 DBA cases were investigated, all of which met the inclusion
criteria
 Age less than 1year.
 Macrocytic anemia with no other significant cytopenia.
 Reticulocytopenia.
 Normal marrow cellularity with a selective paucity of erythroid precursors

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EPIDEMIOLOGY
During the research period 74 (0.4%) individuals
were diagnosed with DBA
34 % of the population had congenital defects,
with the most common malformations being
• Cleft lip/palate, was found in 52% of cases
• In 28% of instances, thumb and upper limb anomalies
were found.
• Heart and urogenital abnormalities were discovered in
12% and 8% of the patients, respectively.

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ETIOLOGY
 Erythroid progenitors and precursors are extremely susceptible to apoptotic
death in DBA, which leads to erythropoietic failure.
 DBA is a polygenic illness in which 20 of the 80 RP genes that code for the
whole ribosome are mutated.
 Deletions in six of the 20 genes found, notably RPS19, RPL5, RPS26,
RPL11, RPL35a, and RPS24, account for 70% of all DBA cases.
 The second most prevalent genetic anomaly in DBA after RPS19 gene
mutation (25%) is substantial deletions, which have been found in 20% of
patients.

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Genes involved in DBA Incidence
RPS19 25%
RPS24 2%
RPL5 6.6%
RPL11 4.8%
RPS10 2.6%
RPS26 6.4%
Table 1: Incidence of genes involved in DBA

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Graphical representation of
Incidence of genes involved in
DBA

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CLINICAL FEATURES
 DBA is characterized by a macrocytic moderate or severe anemia
in association with a regenerative bone marrow and
reticulocytopenia.
 The disorder is also characterized by elevated erythrocyte
adenosine deaminase (eADA) activity in over 75% of cases.
 Congenital anomalies mainly involve the head, upper limbs, heart
and genitourinary system reported to the NorthAmerican DBA
Registry.

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Sr. No. Organ System Defect
1. Craniofacial Hypertelorism, cleft lip or palate, high arched palate,
microcephaly, micrognathia, microtia, low-set ears, low hairline,
epicanthus, ptosis
2. Ophthalmological Congenital glaucoma ,Strabismus, congenital cataract
3. Neck Short neck, Webbed neck, Sprengel deformity, Klippel
Feil deformity
4. Thumb Triphalyngeal, Duplex or bifid, Hypoplastic, Flat thenar eminence,
Absent radial artery
5. Urogenital Absent kidney, Horseshoe kidney, Hypospadias
6. Cardiac Ventricular septal defect, Atrial septal defect, Coarctation of the aorta,
Complex cardiac anomalies
7. Neuromotor Learning difficulties
Table 2: Various congenital anomalies involved in DBA

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Strabismus
Cleft lip & palate Sprengel deformity
Triphalyngeal thumb
Congenital anomalies in DBA

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DIAGNOSIS
DBA is associated with an increased eADA activity .
"eADA is a critical enzyme of the purine salvage pathway, which enables the
deamination of adenosine in inosine and 2’-deoxyadenosine deamination in
deoxyinosine."
The test is not frequently available and is currently performed in only one lab
in each of the following countries: the United States, France, Germany, Italy,
Poland, Israel, and Turkey.
It should be emphasised that the test must be performed on fresh blood samples
or those held at 4°C for less than a few days, as well as on samples prior to red
cell transfusions.

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DIAGNOSIS
Other biological tests for DBA diagnosis are
 Erythropoietin (EPO) level is continuously high in DBA
due to
 ineffective erythropoiesis,
 adequate renal response to anaemia,
 and quantitative deficit of EPO receptors that bind
EPO as a result of significant drops in the number of
erythroid precursors,
 Immunophenotyping and IgG/IgA agglutinin titer.
 Rarely, mostly in adults, a DAT test in conjunction with
an erythroid clonogenic in vitro culture assay with and
without the patient's sera may be useful to rule out
immunological erythroblastopenia in dubious DBA
instances.

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PATHOPHYSIOLOGY
DBA is a genetic defect in erythropoiesis
that results from blockage between the burst
forming unit-erythroid (BFU-E) and colony
forming unit-erythroid (CFU-E) stages, or
between the EPO-independent and EPO-
dependent stages of erythroid development.
The pathophysiology of DBA has shown the
involvement of two main mediators i.e.
• GATA1
• p53

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PATHOPHYSIOLOGY
 GATA1:
 GATA1 encodes a transcription factor which is essential for erythroid differentiation .
The mutation in the GATA1 gene is a Guanine-Cytosine (G→C) transversion at
location 48,649,736 on the X.
 This G→C transversion is associated with X-linked form of DBA, leading to the
substitution of leucine to valine at amino acid 74 of GATA1.
 This aberration affects GATA1 splicing processes and leads to termination of the full-
length GATA1 protein level and synthesis of a short isoform what we call GATA1
short (GATA1s)
 Short ribonucleic acids (shRNA) were employed to produce RP deficiency in normal
CD34+ cells and validate the function of GATA1 in DBA patients.
 they discovered a drop in the level of full-length GATA1 protein and problems in
erythroid development.

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Pathophysiology of DBA involving
GATA1

17.  p53:
DBA have led to the formulation of “ribosomal stress” hypothesis in which reduced RP synthesis
activates p53​
several cytoplasmic free RPs such as RPL11, RPl5, RPL23, RPS7, and RPS27 will bind to
Murine double minute (MDM2) and hinders its interaction with p53,
that induces the downstream events and leads to cell cycle termination or apoptosis.
Finally, this phenomenon results in the DBA phenotype of anemia, deprived growth and
results in congenital abnormalities

18. The pathophysiology of DBA may also be explained by another
theory:
Autophagy, Imbalance b/w decreased globin synthesis & free heme
generate active oxygen species
Increased apoptosis
leads to death of erythroid progenitors & precursors

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Genotype & Phenotype correlation
The phenotypic spectrum of DBA has a broader range of severity, even among the same families,
ranging from the classical condition to those with a single rise in eADA.
Clinical data from European and American DBA cases revealed that the incidence of malformations in
RPS19-mutated DBA patients is 31%.
Comparatively, mutations in RPL5 and RPL11 may result in a more severe phenotype than mutations in
RPS19, particularly in terms of skeletal deformations.
Craniofacial, congenital heart, and thumb abnormalities are more severe in RPS5 mutations than in
RPL11 and RPS19 pathogenic variants.
Cleft lip and/or palate and/or cleft soft palate are more common in patients with RPL5 mutations.
Pathogenic RPL11 mutations are primarily linked to thumb deformities.
Individuals with mutated variants of RPS10, RPS19, RPS26, RPS29,RPL27 & RPL31 have not yet
shown any genotype-phenotype correlations.
DBA with mandibulofacial dystosis (a genetic disorder, which affects the development of facial bones
and tissues) was seen in RPS28 and TSR2 mutants.

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TREATMENT:
The only effective treatment (for the
hematologic problems) for DBA at
this time is bone marrow
transplantation, which is now the
standard of care.
Cross section analysis of the DBAR
reveals that:
• only 37% of patients remain
on steroid therapy,
• 31% receive chronic transfusion
therapy,
• 13% are in remission,
• 9% have undergone HSCT, and 9%
are deceased.

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Corticosteroid therapy & toxicity
Corticosteroids are still the mainstay of DBA treatment.
Approximately 80% of DBA patients respond to an initial course of
steroids.
An increase in haemoglobin is often noticed two to four weeks after
beginning steroid medication.
The dose is then decreased to find the lowest dosage needed to maintain
transfusion independence.
In steroid responders, the maintenance dose varies greatly, with some
individuals requiring extremely low doses.
In over 20% of DBA patients Steroid therapy may have to be
discontinued due to unacceptable side effects.

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Corticosteroid therapy & toxicity
Premature infants receiving steroid therapy have a decrease in growth velocity
Steroid therapy is not generally recommended in babies under6 months of age.
Prednisone, or Prednisolone, is most commonly used
The recommended starting dose is 2 mg/kg of prednisone
once the patient responds, the steroids should be weaned to an average daily dose of1 mg/kg per
day over 8–12 weeks.
In over 20% of DBA patients Steroid therapy may have to be discontinued due to unacceptable side effects.
The dose should then be further tapered slowly to find the minimal maintenance dose necessary to
keep the hemoglobin in the range of 80–100 g/l

24. 1. COSMETIC HIRSUITISM, MOON FACE, FACIAL ERYTHEMA, STRIAIE, ACNE, WEIGHT GAIN
2. Behavioral Hyperactivity, depression, Psychosis
3. Endocrine Adrenal suppression, impaired glucose tolerance, diabetes mellitus, menstrual irregular
ities
4. Fluid
And electrolytes
Hypertension,hypokalemia, Hypocalcemia
5 Skeletal Osteopenia,avascular necrosis, Fractures
6. Growth Impaired growth velocity, especially At puberty
7. Muscular Myopathy affecting proximal muscles
8. Immunosuppression Varicella, pneumocystis pneumonia, Candida
9. Ophthalmological Cataract
10. Neurological Pseudotumor Cerebri
11. Gastrointestinal Gastritis, Perforation, pancreatitis
12. Cardiovascular Hypertension
Steroid side effect

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Transfusion therapy:​
When the patient is not responding to corticosteroids,
continuous transfusion therapy with packed red blood
cells is started after an initial period of transfusion
at diagnosis.
Since suppression of erythropoiesis is not a goal of
transfusion in DBA, as it is in thalassemia major, trough
hemoglobin levels of 80 g/l are usually acceptable
for maintaining adequate growth and development.​

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Evaluation of iron:
In the reticuloendothelial system, macrophages release iron from
the oxidation of red blood cells.
Since iron is not recycled into new red cells in DBA and there is
no specialised route for elimination, iron accumulates in tissues,
leading to significant iron-induced injury in the heart, liver,
pancreas, thyroid, and other organs.
In a 10-year prospective study , an optimal range of liver iron
of 3–7mg/g (dry weight) is suggested

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Evaluation of iron:
Magnetic susceptometry (SQUID) and magnetic resonance
imaging are techniques used to measure liver iron (MRI)
An assessment of liver iron concentration is recommended
every 12–18 months
Detailed endocrine evaluation, including bone
densitometry, is recommended at intervals based on age,
compliance with chelation therapy andiron status

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Chelation therapy:
Chelation should begin when the hepatic iron content reaches 6-7
mg/g, dry weight, or roughly 170-200 ml/kg of transfused packed
red cells.
Delaying iron chelation increases the danger of tissue deposition,
which can lead to organ malfunction and morbidity, while starting it
too soon could cause toxicity from the chelator.
Standard chelation has been limited to the use of deferoxamine
(Desferal-, Novartis), starting at a dose of 40 mg/kg by subcutaneous
infusion over 8-12 h, 4-6 nights per week.
Regular ocular and audiological (for high frequency hearing loss)
examinations are used to monitor deferox-amine toxicity.

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Chelation therapy:
 Two oral chelators currently in use are
 Deferiprone (L1,Apopharma, not licensed in the USA)
 is a bidentate oral iron chelator, which at higher doses has been shown in
non-randomized studies to increase the cardiac T2*more than
deferoxamine.
 Serious toxicity includes arthritis, sometimes severe, and neutropenia.
 Exjade
 is now approved in the United States as first line therapy for transfusional
iron overload in patients two years and older

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Hematopoietic stem cell transplantation:
Hematopoietic stem cell transplantation (HSCT) is curative in DBA
According to the Italian and German DBA registries, nine of 11 patients and
20 of 22 patients were successfully transplanted.
In general, patients with DBA, whether steroid-responsive or transfusion-
dependent, may be considered for transplantation before the age of 10, and
preferably between the ages of 2 and 5 years, if an HLA-matched related
donor is available.

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Gene therapy:
Gene therapy is under development for rps19 deficient DBA
Currently, it has been demonstrated that forced expression of rps19
enhances erythroid formation in primary cells from patients in vitro.
Model systems with rps19deficiency in primary human hematopoietic
cells have been generated
The roadmap to develop a human gene therapy protocol is expected to
take atleast 5 years.

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CONCLUSION:
 In conclusion, DBA is a fascinating and complex erythroid disorder, as illustrated
from the study of the DBA family we described. Progress is being made in our
understanding of the molecular basis for DBA, pathophysiology of the disease, and
developing and pursuing new therapeutic options. In this review we studied that these
advances will enable better clinical management of the patients with DBA in the
coming years. DBA diagnosis requires a correlation between examination findings
and laboratory abnormalities demonstrating macrocytic anemia, elevated hemoglobin
F levels, high erythrocyte deaminase activity, and confirmation with bone marrow
biopsy and gene karyotyping.