FOXP4 and ventricular septal defect: But interestingly, in the literature one individual has been reported with developmental delays, laryngeal hypoplasia and a ventricular septal defect, and a homozygous truncating FOXP4 variant: c.815del; p.(Leu272Profs*95).11 Both parents were shown to be heterozygous for this variant, suggesting autosomal recessive inheritance, but no further clinical details were reported on the parents or other family relatives.