Role of genetic testing for developmental disability

Developmental disability is highly heterogeneous, encompassing syndromic and non-syndromic forms with severity that ranges from mild to profound. Although environmental causes of developmental disability remain important (eg prenatal alcohol exposure, congenital viral infection), genetic factors account for the majority of cases.

The role of the general practitioner in the assessment and diagnosis of developmental delay and disability is outlined in Initial assessment in general practice. Although the diagnostic approach is similar across developmental disability presentations, a specific genetic cause is more likely to be detected in more severe and syndromic forms than in mild and non-syndromic forms.

Identification of a specific cause for developmental disability can have multiple benefits; see Deciding whether to perform a genetic test. The field of genetic testing has advanced in the last decade, with the proportion of individuals with developmental disability in which a specific genetic cause can be identified increasing from around 10% to 50%. This improvement has been driven by chromosome microarray and next generation DNA sequencing (NGS).

Genetic testing for developmental disability may also be performed during pregnancy (prenatal testing) or prior to pregnancy (preconception carrier screening). For advice on prenatal and preconception testing, see the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) guidelines.

The New South Wales Agency for Clinical Innovation has clinical genetics resources, including education and links to relevant professional and consumer organisations.