Greig Cephalopolysyndactyly Syndrome (GCPS) is a very rare multiple congenital anomaly with an estimated incidence of 1-9:1,000,000 in newborns with principal findings of macrocephaly, ocular hypertelorism, and polysyndactyly (preaxial or mixed preaxial and postaxial). Very few cases of prenatal diagnoses have been reported. The postnatal diagnosis is based on clinical findings and family background. GLI3, the only gene associated with this anomaly, is altered in more than 75% of cases. Deletions over 1 Mb and involving other genes yield severe clinical cases, which are known collectively as Greig Cephalopolysyndactyly-contiguous gene Syndrome. We report a case in which, despite early polydactyly findings on week 16, the diagnosis was established during the third trimester of pregnancy due to the late presentation of other anomalies corresponding to this syndrome.

Greig cephalopolysyndactyly syndrome (GCPS) is a rare genetic disorder (about 200 cases reported), characterized by macrocephaly, hypertelorism, and polysyndactyly. Most of the reported GCPS cases are the results of heterozygous loss of function mutations affecting the GLI3 gene (OMIM# 175700), while a small proportion of cases arise from large deletions on chromosome 7p14 encompassing the GLI3 gene. To our knowledge, only 6 patients have been reported to have a deletion with an exact size (given by genomic coordinates) and a gene content larger than 1 Mb involving the GLI3 gene. This report presents a patient with Greig cephalopolysyndactyly contiguous gene syndrome (GCP-CGS) diagnosed with a large, 18 Mb deletion on chromosome 7p14.2-p11.2. Similar cases are reviewed in the literature for a more accurate comparison between genotype and phenotype.