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Genetics ..A few syndromes

Genetics ..A few syndromes. Dr.S.Chakravarty. Down syndrome. 21 trisomy – most common cause: nondisjunction; 2 nd commom cause: mosaics; 3 rd : Robertsonian translocation on 22 chromosomes

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Genetics ..A few syndromes

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  1. Genetics ..A few syndromes Dr.S.Chakravarty

  2. Down syndrome • 21 trisomy – most common cause: nondisjunction; 2ndcommom cause: mosaics; 3rd: Robertsonian translocation on 22 chromosomes • Most common trisomy and most common cause of Mental retardation; • Chance of Down syndrome increases with Maternal age(VERY HIGH AFTER 35) • Alzheimer’s disease and acute lymphoblastic leukemia (ALL).

  3. Down syndrome • Nuchal translucency, endocardial cushion defects and duodenal atresia- 1st trimester Ultra sound; • short neck, single palmar creases, clinodactyly, wide gap between the first and second toes, and hypotonia.

  4. Edward syndrome • Trisomy 18; • Clenched hands with overlapping digits, rocker bottom feet, cardiac defects; • Profound occiput, micrognathia; • Horse shoe kidneys

  5. Patau syndrome • Trisomy 13; • Microcephaly and Holoprosencephaly; • Facial and eye abnormalities, cleft lip and palate, omphalocele, polydactyly, congenital heart defects, renal abnormalities

  6. Turner syndrome

  7. Turner syndrome • Deletion of a X chromosome (Genotype:45,X0); • Phenotypically female, No Barr body; • Ultrasonography, which shows cystic hygroma, chylothorax, asictesand hydrops; • short stature and infertility from streak gonads, neck webbing, low posterior hair line, broad chest, cubitusvalgus, coarctation of the aorta, renal anomalies. • Primary amennorhea;

  8. Klinefelter syndrome

  9. Klinefelter syndrome • 47, XXY: incidence increases with paternal age; • Phenotypically males; Only one X is functional, the other is a Barr body; • Extra X can be derived from either dad or mom due to non-disjunction. • Hypogonadism, poor development of secondary sexual characteristics. • Tall stature, Gynecomastia. • Decreased testosterone and increased FSH and LH

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