Partial Duplication of 18q Including a Distal Critical Region for Edwards Syndrome in a Patient with Normal Phenotype and Oligoasthenospermia: Case Report

Several authors have attempted to construct a phenotype map for duplications of different portions of chromosome 18 to identify a possible critical region (CR) for Edwards Syndrome. Partial duplications of 18q have been reported in the literature involving the distal CR in patients with some clinical features of Edwards Syndrome. Here, we describe a phenotypically normal male with a large duplication on chromosome 18 that involves the proposed distal CR. The lack of clinical features is remarkable, except for pathological semen analysis, which suggests that terminal 17.4 Mb of 18q do not contain the Edwards Syndrome CR. Alternatively, unknown modifier factors or undetected somatic mosaicism might cause incomplete penetrance of this duplication.