第八章 遗传代谢性疾病（The eighth chapter is inherited metabolic disease）.docVIP

第八章 遗传代谢性疾病（The eighth chapter is inherited metabolic disease） The eighth chapter is inherited metabolic disease Trisomy 21 syndrome Trisomy 21 syndrome (21trisomysyndrome) or Down syndrome also called Down syndrome, [genetics foundation] Cytogenetic features of chromosome twenty-first was three (trisomy 21), the symptom is mainly due to the occurrence of germ cells in meiosis to produce gametes, or fertilized eggs in a mitotic chromosome 21 occurred are not isolated, the embryo somatic memory in an additional 21 chromosomes. [clinical presentation] The main features of the disease are mental retardation, special facial features and growth retardation, and may be accompanied by multiple malformations. 1. most of the children with mental retardation have different degrees of mental retardation, which is becoming more and more obvious with age. Block If the proportion of normal cells in the children with syncytial type is larger, the mental retardation is less. 2. growth retardation in children born of height and weight were lower than the normal children after birth, physical development, motor development was slow, short stature, bone age behind the actual age, to delayed and abnormal sequence; short limbs, joint ligament relaxation, excessive bending; hypotonia, abdominal distention, accompanied by umbilical hernia; the little finger is short, stubby fingers, middle phalanx, short and wide, and bent inwards. 3. special faces are born with a distinct distinctive face (Figure 8 - 1) with a dull expression. Small eyes, wide between the eyes, eyes with oblique lateral canthus, epicanthus; flat nose, small ear; narrow palate, often tongue mouth, drooling; small round head, large anterior fontanelle and close delay; short and wide neck. 4., skin pattern features can be through hand, palm Trident point t moved to the palm, ATD angle increased (Figure 8 - 2), fifth fingers, some only one finger wrinkles. 5. accompanied by malformations, about 50% of children with congenit