Overlap of PIV syndrome, VACTERL and Pallister-Hall syndrome: clinical and molecular analysis

The polydactyly, imperforate anus, vertebral anomalies syndrome (PIV, OMIM 174100) was determined as a distinct syndrome by Say and Gerald in 1968 (Say B, Gerald PS. Lancet 1968: 2: 688). We noted that the features of PIV overlap with the VATER association and Pallister-Hall syndrome (PHS, OMIM 146510), which includes polydactyly, (central or postaxial), shortened fingers, hypoplastic nails, renal anomalies, imperforate anus, and hypothalamic hamartoma. Truncation mutations in GLI3, a zinc finger transcription factor gene, have been shown to cause PHS. We performed a molecular evaluation on a patient diagnosed with PIV, whose mother, grandfather, and maternal aunt had similar malformations. We sequenced the GLI3 gene in the patient to determine if she had a mutation. The patient was found to have a deletion in nucleotides 2188-2207 causing a frameshift mutation that predicts a truncated protein product of the gene. Later clinical studies demonstrated that the patient also has a hypothalamic hamartoma, a finding in PHS. We concluded that this family had atypical PHS and not PIV. This result has prompted us to re-evaluate the PIV literature to see if PIV is a valid entity. Based on these data and our examination of the literature, we conclude that PIV is not a valid diagnostic entity. We conclude that patients diagnosed with PIV should be reclassified as having VACTERL, or PHS, or another syndrome with overlapping malformations.