Congenital diaphragmatic hernia and early lethality in PIGL-related disorder

We report on three male siblings who presented prenatally with a nearly identical combination of congenital anomalies and who died shortly after preterm birth. The first baby was a singleton pregnancy, and the other two babies were dichorionic diamniotic twins. Key features included: left-sided congenital diaphragmatic hernia, inferior vermian dysgenesis/hypoplasia, prenasal edema, cleft palate, micropenis/ambiguous genitalia (in 2 of 3 babies), bilateral renal pelvic dilatation (in twins, first baby showed slightly enlarged kidneys) and polyhydramnios (in 2 of 3). Whole genome sequencing performed on DNA from all three babies revealed homozygous missense PIGL gene variants: c.438C>A, p.(Phe146Leu). Both parents were heterozygous carriers of the variant. The reporting clinical laboratory classified the change as a variant of uncertain significance (VUS), and concluded "A genetic diagnosis of autosomal recessive CHIME syndrome is possible". The PIGL gene has been reported to cause two different autosomal recessive conditions: CHIME syndrome and Mabry syndrome. CHIME (Zunich neuroectodermal syndrome) is characterized by ocular Colobomas, Heart defects, Ichthyosiform dermatosis, Mental retardation (intellectual disability), and Ear anomalies, including conductive hearing loss. Mabry [aka hyperphosphatasia mental retardation syndrome (HPMRS)] is characterized by severe developmental delay, moderate to severe intellectual disability, distinctive facial features, brachytelephalangy, increased serum levels of alkaline phosphatase (ALP), and recurrent seizures. Neonatal demise and lack of postmortem examination precluded assessment of some key features (including seizures, developmental delay, ALP levels, colobomas and deafness), but overlapping features observed included cleft palate, brain anomalies, genitourinary abnormalities and prenasal edema. Notably, diaphragmatic hernia is not a common feature of either condition, but is a cardinal feature of Fryns syndrome. The genetic etiology of Fryns syndrome has not been definitively established, although, much like CHIME and Mabry syndrome, can be caused by variants in glycosylphosphatidylinositol (GPI) anchor pathway genes. Our findings suggest further overlap between inherited GPI deficiencies, and possible expansion of the clinical phenotype of PIGL-related disorders to include prenatal presentations with congenital diaphragmatic hernia. Although reported as a VUS, we present phenotypic and familial segregation evidence that supports likely pathogenicity of the c.438C>A variant.