MED27, SLC6A7, and MPPE1 Variants in a Complex Neurodevelopmental Disorder with Severe Dystonia.

Background: Despite advances in next generation sequencing technologies, the identification of variants of uncertain significance (VUS) can often hinder definitive diagnosis in patients with complex neurodevelopmental disorders.

Objective: The objective of this study was to identify and characterize the underlying cause of disease in a family with two children with severe developmental delay associated with generalized dystonia and episodic status dystonicus, chorea, epilepsy, and cataracts.

Methods: Candidate genes identified by autozygosity mapping and whole-exome sequencing were characterized using cellular and vertebrate model systems.

PIGF deficiency causes a phenotype overlapping with DOORS syndrome.

DOORS syndrome is characterized by deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures. In this study, we report two unrelated individuals with DOORS syndrome without deafness. Exome sequencing revealed a homozygous missense variant in PIGF (NM_173074.