临床医学1教学课件.ppt

Reciprocal Translocation after meiosis and fertilization 1/18 normal, 1/18 carrier, 8/9 abnormal 总染色体物质无增加或减少 通常表型正常 但生育问题： 反复流产、宫内死胎、死产、出生缺陷 染色体异常携带者 染色体病患者以外的染色体异常 平衡染色体结构异常-染色体病携带者 Single gene defects Caused by an individual mutant gene and transfer through the generations according to Mendelian genetics Individual incidence rate is rare Total incidence is 1.00% in live births and 6-8% in hospitalized children (2) 单基因病 Monogenic disorder Balanced translocation in meiosis and offsprings High Risk to produce unbalanced offspring 2:2 separation 1．常染色体显性遗传病?  Autosomal Dominant The trait appears in every generation Any child of an affected person has a 50 percent risk of inheriting the trait. Unaffected family members do not transmit the trait to their children The occurrence and transmission of the trait are not influenced by sex Ocular (眼) Lens dislocation (晶状体脱位) Cardiovascular (心血管) Aortic anomalies (主动脉畸形) Mitral valve prolapse (二尖瓣脱垂) Musculoskeletal (肌肉骨骼) Change of height/span(指距)and US/LS Pectus deformities(胸畸形) Dural ectasia (硬脊膜膨出) Marfan Syndrome Clinic Features Blue sclera Bone fragility Short stature Dentinogenesis insufficiency Hearing loss Reduced life span Osteogenesis Imperfecta (OI) （成骨发育不全） Huntington Disease (HD) Onset: 35 to 44 ys (delayed onset) A progressive disorder of motion, cognitive, and psychiatric disturbances The median survival time: 15 to 18 years after onset dilatation of ventricles, atrophy of caudate nucleus 2． 常染色体隐性遗传病 Autosomal Recessive The trait characteristically appears only in sibs, not in their parents. On the average, one fourth of the sibs of the proband are affected The parents of affected child may be consanguineous. Males and females are equally likely to be affected. Albinism白化病 A group of recessive genetic disorders of melanin synthesis resulting in congenital hypopigmentation(色素沉着不足).