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Genetic counseling - Dr.Padmesh


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Genetic Counseling (DNB Solved)

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Genetic counseling - Dr.Padmesh

  1. 1. GENETIC COUNSELING DNB Pediatrics solved answers, Dr.Padmesh. V *WHO definition of counseling: ‘Genetic counselling is the process through which knowledge about the genetic aspects of illnesses is shared by trained professionals with those who are at an increased risk or either having a heritable disorder or of passing it on to their unborn offspring.’ *Indications for Genetic Counseling: (Nelson) 1.Advanced parental age -Maternal age ≥35 yr -Paternal age ≥50 yr 2.Previous child with or family history of -Congenital abnormality -Dysmorphology -Mental retardation -Isolated birth defect -Metabolic disorder -Chromosome abnormality -Single-gene disorder 3.Adult-onset genetic disease (presymptomatic testing) -Cancer -Huntington disease 4.Consanguinity 5.Teratogen exposure (occupational, abuse) 6.Repeated pregnancy loss or infertility 7.Pregnancy screening abnormality -Maternal serum α-fetoprotein -Maternal triple screen or variant of this test -Fetal ultrasonography -Fetal karyotype
  2. 2. 8.Heterozygote screening based on ethnic risk -Sickle cell anemia -Thalassemias -Tay-Sachs, Canavan, Gaucher diseases 9.Follow-up to abnormal neonatal genetic testing *FIVE STEPS IN GENETIC COUNSELING: (IAP Textbook) 1. Reaching at a DIAGNOSIS : 2. Risk Assessment, including risk of Recurrence: 3. Communication: 4. Discussion of Options: 5. Long term contact and support: STEP 1. Reaching at a DIAGNOSIS : Not always straight forward! 1. First step is construction of a family tree: -Pattern of inheritance can be obtained from Pedigree analysis. -Various pedigree symbols 2. History taking: 3. Clinical Examination: -Complete physical examination -Anthropometric measurements -Accurate description of facial features & other malformations -A photographic record can be very useful -Examination of the parents and other relatives 4. Investigations: -Hematological, Biochemical investigations, Imaging studies
  3. 3. -Special tests like Chromosomal analysis, Enzyme assays -DNA analysis STEP 2. Risk Assessment, including risk of Recurrence: a) Detection of carriers: - ‘Carrier’ is an individual who possesses the gene determining an inherited disease in heterozygous state & who is essentially healthy at the time of study. -Identifying carriers plays an important role in preventing genetic diseases. b) Estimation of mathematical risk from the data obtained from pedigree. c) Known data about recurrence risk: (in %) Disorder M:F Normal parents having Affected parents 2nd affected child having an affected child 2nd affected child CDH 1:6 4 4 10 CTEV 2:1 3 3 10 Spina bifida 2:3 5 3 - Cleft palate 2:3 2 7 15 Cleft lip +palate 3:2 4 4 10 Asthma 1:1 10 26 - DM 1:1 8 8 10 STEP 3. Communication: -Counseling to be started as early as possible. -Rapport with both parents -Both parents must be present during counseling.
  4. 4. -Describe genetic basis of disease using simple language and visual aids. -Parents/Relatives should be encouraged to clarify their doubts. COUNSELING SESSIONS MUST INCLUDE INFORMATION ON: (Nelson) 1. Information about specific condition/disorder. 2. If specific diagnosis cannot be made,explain the differential diagnosis & the emperical options. 3. Natural History of the condition. 4. Genetic aspects & recurrence risk. 5. Options about Pre-natal diagnosis & prevention. 6. Referral to genetic specialist or endocrinologist or other specialists as required. STEP 4. Discussion of Options: Discuss about options available,like: - Prenatal diagnosis - Abortion - Not having children - Adoption Non-directiveness: The main principle of genetic counseling is NON- DIRECTIVENESS which is the art of presenting facts WITHOUT influencing decisions. STEP 5. Long term contact and support: Combined approach involving -Parents -Genetic counselor -Family physician -Social worker -Other medical specialties -Support groups
  5. 5. (Reference: Nelson, IAP Textbook of Pediatrics, Genetics for Clinicians by Shubha Phadke, Genetics 2009 conference proceedings. )
  6. 6. (Reference: Nelson, IAP Textbook of Pediatrics, Genetics for Clinicians by Shubha Phadke, Genetics 2009 conference proceedings. )