第四章 人类染色体与染色体病PPT.ppt

Direct Insertion Structural Aberration Inverse Insertion Structural Aberration Chromosome Disease in Clinical Clinical feature The general features in autosome abnormalities are a triad of growth retardation, mental retardation, and specific somatic abnormalities. Change of sex chromosome also have the abnormalities and malformations of internal or external genital organs. Down Syndrome (trisomy 21 syndrome) Chromosome Disease in Clinical Characteristics Growth retardation Varying degrees of mental retardation Flattened face Upward slanting of the eyes with epicanthal folds(内眦赘皮) 1 in 600 ~ 800 newborns Chromosome Disease in Clinical Down Syndrome (trisomy 21 syndrome) 1. Trisomy —— 95%, 47, XX(XY), ＋21 Caused by non-disjunction of chromosome 21, correlated with age of mother. Chromosome Disease in Clinical Down Syndrome (trisomy 21 syndrome) Karyotype of affected： 46, XX(XY), －14, ＋t(14q21q) 2. Mosaic —— 2% ~ 4%, 46/47 3. Unbalance translocation Karyotype of balance carrier： 45, XX(XY), －14, －21, ＋t (14q21q) Chromosome Disease in Clinical 1. Trisomy —— 92.5%, 47, XX(XY), ＋21 Down Syndrome (trisomy 21 syndrome) 1 in 3500 ~ 8000 newborns Edwards Syndrome (trisomy 18 syndrome) Characteristics Growth retardation Mental retardation Congenital heart disease Rocker-bottom feet fixed flexion deformity of the fingers Chromosome Disease in Clinical Chromosome Disease in Clinical 1 in 3500 ~ 8000 newborns Edwards Syndrome (trisomy 18 syndrome) 1 in 25 000 newborns Patau Syndrome (trisomy 13 syndrome) Characteristics Varying degrees of mental retardation Cleft lip Cleft palate Polydactyly (postaxial) Equinovarus Chromosome Disease in Clinical 1 in 50000 newborns 5p- Syndrome (Cat Cry syndrome) Characteristics Round, moon-shaped face “Cry of the cat” Varying degrees of mental retardation Low set ears Chromosome Disease in Clinical Turner Syndrome (45, X) 1 in 5000 liveborn females Characteristics Short stature Webbed neck Ovarian dysgenesis, primary amenorrhea, infertil