Common chromosomal disorders

Abnormalities of the autosomal chromosomes generally cause
multiple congenital malformations and mental retardation.
Children with more than one physical abnormality and
developmental delay or learning disability should therefore
undergo chromosomal analysis as part of their investigation.
Chromosomal disorders are incurable but most can be reliably
detected by prenatal diagnostic techniques. Amniocentesis or
chorionic villus sampling should be offered to women whose
pregnancies are at increased risk – namely, couples in whom
one partner carries a balanced translocation, women identified
by biochemical screening for Down syndrome and couples who
already have an affected child. Unfortunately, when there is no
history of previous abnormality the risk in many affected
pregnancies cannot be predicted before the child is born.