Down’s syndrome

Best-known and commonest congenital disorder, previously called mongolism because of its effect on the set of the eyes. The condition is associated with mental deficiency and occurs in 1 in 600 live births. The percentage is higher in babies born to older mothers. Many congenital disorders occur as the result of an error of cell division in the fertilized ovum; in Down’s syndrome the ovum has received two many chromosomes, 47 instead of the normal 46; chromosome 21 is represented three times instead of twice (trisomy 21), although other deviations are possible. Heredity affects only 1 to 2 per cent of cases. The outward signs of Down’s syndrome are usually clear at birth, but not always recognized, because the baby’s behaviour is not significantly different from the norm. After a few weeks or months the baby’s backwardness shows clearly. The most important characteristics are a slight slant in the eyes running from underneath on the inside to above on the outside; pelicanthus (a fold of skin over the inner corner of the eye); a small round head flattened at the back; a short neck; occasionally misshapen ears; and a large, deeply-grooved tongue which often protrudes from the mouth. The hands are plump, with a short, crooked little finger, and fold of skin in the palm. The children are short and plump, often very listless, particularly in the first year of life, and frequently also have congenital skin abnormalities. Training these children often presents difficulties from the first; the babies are strikingly quiet and listless, often have breathing problems, and feeding them can be very hard. They are also particularly prone to infection. Diagnosis can usually be made with ease from outward characteristics, and confirmed by chromosome tests and study of the folds in the palms of the hands. There is no treatment for the condition. The children are often affectionate and dependent, and can be brought up in their own family for a long time, with the help of the family doctor, district nurse, health centre and social workers. Over the years the child may demand too much attention, or need specialist help, in which case admission to a suitable institution may be necessary. Parents with an increased risk of having such children have the opportunity to receive genetic counselling and the pregnant mother’s amniotic fluid may be examined for the chromosome anomaly.

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