Case Report: A novel de novo heterozygous truncating mutation in MED12L identified in a Chinese autistic boy

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder. A previous study by Nizon et al. indicated that some children with intellectual disability (ID) carrying de novo MED12L mutations exhibited mild to moderate autistic features. However, the relationship between MED12L and ASD remains unclear.

Here we reported a male child with severe autistic features carrying a novel de novo heterozygous truncating mutation of MED12L (NM_053002.5:c.586C>T, p.(Arg196Ter)). He was diagnosed with ASD according to ICD-11 and DSM-5 criteria. Clinical examination indicated that this child exhibited severe autistic features and several dysmorphic features, including a flat nasal bridge, bulbous nasal tip, thin upper lip, and triangular face. Magnetic resonance imaging (MRI) of the brain revealed an enlarged perivascular space in the right temporal lobe.

This case demonstrates that this de novo heterozygous truncating mutation in MED12L may be involved in the development of ASD, and haploinsufficiency of MED12L may be associated with severe autistic features. Obvious clinical manifestations and dysmorphic features in this child with a truncating mutation in MED12L expand the phenotypic spectrum of MED12L-related cases and warrant further functional studies to elucidate the relationship between MED12L and ASD.