This C-to-A point mutation in the Tbc1d32 (TBC1 domain family, member 32) gene was identified in an ENU screen for recessive cardiovascular development phenotypes in Dr. Cecilia Lo's laboratory, NHLBI Cardiovascular Development Consortium (CvDC). It was recovered from G1 sperm and associated with the phenotype described described here. Because G1 sperm were cryopreserved, additional incidental mutations are also segregating in this strain.
Homozygotes demonstrate laterality defects, including PTA (Type A1), overriding aorta, atrioventricular septal defect (AVSD), dual inferior vena cava (IVC), and right atrial isomerism. Excencephaly, craniofacial defect with cleft lip/palate and failure in fusion of the frontonasal prominence, tracheoesophogeal fistula, hypoplastic lungs, eye defects such as anopthalmia and microphthalmia, polydactyly, and cystic/duplex kidneys are also seen.