Table 1.

Clinical features that may be suggestive of a syndromic aetiology for patients with neurodevelopmental disorders

Clinical feature	Definitions and/or examples
Dysmorphic features	Visible morphological findings that differ from those commonly seen in the general population or same genetic ancestry. For example, hypertelorism and syndactyly.
Congenital malformations	A non-progressive morphological anomaly of a single organ or body part that is present at birth. For example, cleft palate, tetralogy of Fallot and polydactyly.
Abnormal head size	Occipitofrontal circumference less than or greater than 2 SD from the mean for age, sex and ethnicity. For example, microcephaly and macrocephaly.
Unexplained growth abnormalities	Growth parameters greater than or less than 2 SD from the mean for age, sex and ethnicity, particularly if parental heights are average. For example, prenatal growth restriction, postnatal failure to thrive, short stature and overgrowth.
Family history consistent with Mendelian inheritance	There are similarly affected individuals related to the proband in a pattern suggestive of an autosomal recessive, autosomal dominant or X-linked condition For example, siblings with similar phenotype and consanguineous parents (may suggest autosomal recessive condition); affected males related through maternal line with similar phenotype (may suggest X-linked inheritance).
Additional medical comorbidities	Medical conditions, particularly when multiple or uncommon, that are not expected to be present secondary to the neurodevelopmental disorder itself. For example, sensorineural hearing loss, vision impairment, renal disease, epilepsy, ataxia and neuromotor deficits.