Genomic alterations in biliary atresia suggest region of potential disease susceptibility in 2q37.3

Biliary atresia (BA) is a progressive, idiopathic obliteration of the extrahepatic biliary system occurring exclusively in the neonatal period. It is the most common disease leading to liver transplantation in children. The etiology of BA is unknown, although infectious, immune and genetic causes have been suggested. Although the recurrence of BA in families is not common, there are more than 30 multiplex families reported and an underlying genetic susceptibility has been hypothesized. We screened a cohort of 35 BA patients for genomic alterations that might confer susceptibility to BA. DNA was genotyped on the Illumina Human Hap 550 Beadchip platform, which analyzes over 550,000 single nucleotide polymorphisms (SNPs) for genomic deletions and duplications. Areas of increased and decreased copy number were compared to those found in control populations. To identify regions that could serve as susceptibility factors for BA, we searched for regions that were found in BA patients, but not in controls. We identified two unrelated BA patients with overlapping heterozygous deletions of 2q37.3. Patient 1 had a 1.76 Mb (280 SNP), heterozygous deletion containing 30 genes. Patient 2 had a 5.87 Mb (1,346 SNP) heterozygous deletion containing 55 genes. The overlapping 1.76 Mb deletion on chromosome 2q37.3 from 240,936,900 to 242,692,820 constitutes the critical region and the genes within this region could be candidates for susceptibility to BA.