Expanding the phenotypic spectrum of MPDZ gene variants: A case report with prenatally detected Dandy–Walker malformation and single ventricle heart

A 19-year-old gravida underwent genetic counseling at the 26th week of gestation due to sonographically detected fetal anomalies, including Dandy-Walker malformation, characterized by cerebellar vermis hypoplasia and an enlarged cisterna magna, and single ventricle heart. Following amniocentesis at the 27th week, after the normal quantitative fluorescence polymerase chain reaction and chromosomal microarray results, trio clinical exome sequencing was performed, revealing a novel homozygous pathogenic variant in the MPDZ gene, c.4576G>T (NM_001378778.1). So far, homozygous and compound heterozygous variants in MPDZ have been strongly linked to congenital hydrocephalus type 2 with or without accompanying brain or eye anomalies. The reported variant, absent in control databases, resulted in premature termination of protein synthesis, consistent with pathogenicity predictions. Both parents were identified as heterozygous carriers. Pregnancy termination was chosen post-diagnosis. Postmortem findings correlated with prenatal ultrasound. Our case broadens the prenatal phenotypic spectrum associated with MPDZ variants, necessitating further studies for comprehensive understanding of molecular mechanisms beneath the clinical manifestations.