GATA4 variant identified by whole-exome sequencing in a Japanese family with atrial septal defect: Implications for male sex development

A case of 46,XY disorders of sex development with congenital heart disease caused by a GATA4 variant

GATA4 is known to be a causative gene for congenital heart disease, but has also now been associated with disorders of sexual development (DSD). We here report a pathogenic variant of GATA4 in a 46,XY DSD patient with an atrial septal defect, identified by whole-exome sequencing to be c.487C>T (p.Pro163Ser). This mutation resulted in reduced transcriptional activity of the downstream gene. When we compared this transcriptional activity level with other GATA4 variants, those that had been identified in patients with cardiac defects and DSD showed less activity than those in patients with cardiac defect only. This suggests that the normal development of the heart requires more strict regulation of GATA4 transcription than testicular development. Further, when the different variants were co-expressed with wild-type, the transcriptional activities were consistently lower than would be expected from an additive effect, suggesting a dominant-negative impact of the variant via dimer formation of the GATA4 protein. Since these pathogenic GATA4 variants are occasionally identified in healthy parents, a threshold model of quantitative traits may explain the cardiac defect or DSD phenotypes that they cause.

De novo AFF3 variant in a patient with mesomelic dysplasia with foot malformation

Mesomelic dysplasia (MD) encompasses a heterogeneous group of disorders characterized by shortening of the middle segments of the limbs. Previous studies have revealed the development of Nievergelt type-like MD accompanied by postaxial toe reduction in a patient with a ~500 kb microdeletion at 2q11.2 involving AFF3 alone, and the occurrence of Nievergelt type-like MD in mice with a ~353 kb deletion involving Aff3, together with strong expression of mouse Aff3 in the developing limbs and zeugopod. We encountered a 2 6/12-year-old Japanese girl with an unclassifiable MD associated with hypoplasia of postaxial toes, and identified a de novo likely pathogenic variant of AFF3 (NM_002285.2:c.697 G > A, p.(Ala233Thr)) by whole exome sequencing. The results provide further evidence for AFF3 being the causative gene for MD with foot malformation which may be termed "AFF3-related MD" or "Steichen-Gersdorf type MD".