A family history of premature CHD or dyslipidaemia, or both, is generally accepted as valid grounds for paediatric screening, although there are some who consider it unjustified even then. The most common indication is FH, where there is a 50:50 chance that the child will be affected if one of the parents is a known heterozygote. A provisional diagnosis can be made at birth by demonstrating an LDL cholesterol concentration of >1.1 mmol/l in cord blood, although this must be confirmed by further testing, preferably in a lipid clinic. Values of total and LDL cholesterol of > 6.7 mmol/l and > 4.0 mmol/l, respectively, in at least two fasting blood samples taken between the ages of 1-16 are regarded as diagnostic of FH.19
Other inherited disorders include familial hypertriglyceri-daemia and familial combined hyperlipidaemia, both of which carry an increased risk of CHD,20 as does type III hyperlipopro-teinaemia, which is commonly caused by homozygous inheritance of the e2 allele. These three disorders show delayed penetrance and are best screened for after puberty. Family screening of children for inherited dyslipidaemias is more cost effective than population screening but is often neglected, despite its relevance to the prevention of premature CHD.
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