Heterozygous Deletion of FOXA2 Segregates with Disease in a Family with Heterotaxy, Panhypopituitarism, and Biliary Atresia
HUMAN MUTATION
Authors: Tsai, Ellen A.; Grochowski, Christopher M.; Falsey, Alexandra M.; Rajagopalan, Ramakrishnan; Wendel, Danielle; Devoto, Marcella; Krantz, Ian D.; Loomes, Kathleen M.; Spinner, Nancy B.
Abstract
Biliary atresia (BA) is a pediatric cholangiopathy with unknown etiology occurring in isolated and syndromic forms. Laterality defects affecting the cardiovascular and gastrointestinal systems are the most common features present in syndromic BA. Most cases are sporadic, although reports of familial cases have led to the hypothesis of genetic susceptibility in some patients. We identified a child with BA, malrotation, and interrupted inferior vena cava whose father presented with situs inversus, polysplenia, panhypopituitarism, and mildly dysmorphic facial features. Chromosomal microarray analysis demonstrated a 277 kb heterozygous deletion on chromosome 20, which included a single gene, FOXA2, in the proband and her father. This deletion was confirmed to be de novo in the father. The proband and her father share a common diagnosis of heterotaxy, but they also each presented with a variety of other issues. Further genetic screening revealed that the proband carried an additional protein-altering polymorphism (rs1904589; p.His165Arg) in the NODAL gene that is not present in the father, and this variant has been shown to decrease expression of the gene. As FOXA2 can be a regulator of NODAL expression, we propose that haploinsufficiency for FOXA2 combined with a decreased expression of NODAL is the likely cause for syndromic BA in this proband.
Familial transposition of the great arteries caused by multiple mutations in laterality genes
HEART
Authors: De Luca, Alessandro; Sarkozy, Anna; Consoli, Federica; Ferese, Rosangela; Guida, Valentina; Dentici, Maria Lisa; Mingarelli, Rita; Bellacchio, Emanuele; Tuo, Giulia; Limongelli, Giuseppe; Digilio, Maria Cristina; Marino, Bruno; Dallapiccola, Bruno
Abstract
Background The pathogenesis of transposition of the great arteries (TGA) is still largely unknown. In general, TGA is not associated with the more common genetic disorders nor with extracardiac anomalies, whereas it can be found in individuals with lateralisation defects, heterotaxy and asplenia syndrome (right isomerism). Objective To analyse genes previously associated with heterotaxy in order to assess mutations in familial TGA unassociated with other features of laterality defects. Methods Probands of seven families with isolated TGA and a family history of concordant or discordant congenital heart disease were screened for mutations in the ZIC3, ACVR2B, LEFTYA, CFC1, NODAL, FOXH1, GDF1, CRELD1, GATA4 and NKX2.5 genes. Results Mutation analysis allowed the identification of three sequence variations in two out of seven TGA probands. A FOXH1 (Pro21Ser) missense variant was found in a proband who was also heterozogous for an amino acid substitution (Gly17Cys) in the ZIC3 gene. This ZIC3 variant was also found in another family member with a second sequence variation (Val150lle) in the NKX2.5 gene homeodomain who was affected by multiple ventricular septal defects. A second proband was found to harbour a splice site variant (IVS2-1G -> C) in the NODAL gene. Conclusions The present study provides evidence that some cases of familial TGA are caused by mutations in laterality genes and therefore are part of the same disease spectrum of heterotaxy syndrome, and argues for an oligogenic or complex mode of inheritance in these pedigrees.