There is evidence to recommend offering specific genetic tests to pregnant women, couples planning a pregnancy, and neonates (as part of the newborn screening program) ©. Other genetic tests are appropriate for certain conditions where the individual is considered to be at increased risk (A). In order to identify patients who may potentially benefit from genetic testing, the GP must ensure that a comprehensive family history is taken from all patients including first-degree or second-degree relatives (A) and regularly updated. A family history should ideally extend to three generations, covering both sides of the family and ethnic background. Age of onset of disease and age of death should be recorded where available. The presence of genetically determined disease may be suggested by increased frequency and early onset of cancers in families, premature ischaemic heart disease or sudden cardiac death, intellectual disability, multiple pregnancy losses, stillbirth or early death, and children with multiple congenital abnormalities. Also, patients of particular ethnic backgrounds may be at increased risk and benefit from genetic testing for specific conditions. Possible consanguinity (cousins married to each other) should be explored, for example, by asking, ‘Is there any chance that a relative of yours might be related to someone in your partner’s family?’. GPs should consider referral to or consultation with a genetic service (general or cancer genetics) for testing because test results, (which rely on sensitivity, specificity and positive predictive value) are not straightforward. Testing often involves complex ethical, social and legal issues. Waiting lists for genetic services are usually more than 1 month, so direct consultation and liaison by telephone are necessary when the genetic advice could affect a current pregnancy. First trimester Down syndrome screening:
• free beta human chorionic gonadotrophin (HCG), pregnancy associated plasma protein at 10–12 weeks (this also provides risk for trisomy 18, Edwards syndrome) • nuchal translucency screen at 11 weeks 3 days–13 weeks 6 days. Second trimester serum screening: • beta HCG, unconjugated oestriol, alpha-fetoprotein and inhibin A ideally at 15–17 weeks; also gives risk for Edward syndrome and NTDs.