|
|
|
|
||||
Anencephaly
Inheritance patterns andprenatal diagnosis
Inheritance patterns
In most cases the aetiology (cause) is unknown but there are some relations with abnormal genes. The risk of a further pregnancy with anencephaly and spina bifida is said to be 1 in 50 if there has been one previously affected pregnancy and 1 in 5 if there have been two previously affected pregnancies. Associated abnormalities include hydro-nephrosis (excessive enlargement of the fluid collecting system for the kidneys), cleft palate and/or palate, diaphragmatic hernia, omphalocoele (abnormal abdominal wall development) and horseshoe kidneys. In addition spinal abnormalities and abnormal postures of the foot are also associated. It has been calculated that risks for a neural tube defect in relatives of affected persons are as follows: father's siblings, seven per cent; mother's sister's children, thirteen per cent; mother's brother's children, three per cent; father's sister's children, six per cent; and father's brother's children, four per cent. Unfortunately, ninety-five per cent of these conditions occur in pregnancies in which there was nothing previously suspicious.
Prenatal diagnosis
Anencephaly can be detected prenatally by ultrasound sometimes as early as fourteen weeks depending on the lie of the fetus. It should be easily visible at twenty weeks on the ultrasound. Amniocentesis and measurement of the levels of alpha feta protein in the amniotic fluid can confirm the diagnosis. Alpha feta protein would be expected to be extremely high in this defect.
How is it diagnosed?
| Is there support? 
Donate Now
makingcontact.org
Pounds for parents
Subscribe to the 