Neu Laxova syndrome and megacystis in the first trimester: Broadening the fetal phenotype

Neu Laxova syndrome (NLS) is a rare and lethal congenital disorder characterized by severe intra‐uterine growth retardation (IUGR), ichthyosis, abnormal facial features, limb abnormalities with arthrogryposis and a wide spectrum of severe malformations of the central nervous system (CNS). NLS is due to biallelic variants in three genes previously involved in serine‐deficiency disorders (PHGDH, PSAT1 and PSPH), extending the phenotypic spectrum of these disorders. Key points What is already known about this topic? Biallelic PHGDH variants are associated with serine‐deficiency disorders and Neu Laxova syndrome (NLS). NLS is characterized by severe IUGR, ichthyosis, abnormal facial features, limb abnormalities with arthrogryposis and a wide spectrum of severe malformations of the CNS. NLS is usually suggested in the third trimester of pregnancy or in the neonatal period. What does this study add? The study reports early and severe presentation of NLS with increased nuchal translucency and megacystis. Our findings suggest that megacystis is secondary to a neurogenic muscular atrophy, extending neuromuscular findings reported in NLS. The study highlights the intrafamilial variability of NLS.