Delineation of the 9q31 deletion syndrome: Genomic microarray characterization of two patients with overlapping deletions.

Interstitial deletions of chromosome 9q31 are very rare. The deletions in most reported patients have been detected by conventional cytogenetics, with reported breakpoints ranging between 9q21 and 9q34. Therefore, an accurate description of a "9q31 deletion syndrome" could not be established. However, based on microarray studies, a small region of overlap has recently been proposed. We report clinical features of two unrelated individuals with overlapping 9q deletions identified by SNP microarray analysis. Patient 1 has a 9 Mb deletion, while Patient 2's deletion was 21.6 Mb. The clinical features common to our patients and those in the literature include developmental delay and short stature. Patient 2 shows additional features not reported in other 9q31 deletions, such as hearing loss, ventriculomegaly, cleft lip and palate, and small kidneys, which could be due to the larger size of the deletion, hence the influence of the genes in the region beyond the smallest region of overlap. Based on the comparison of these patients with the previously reported patients, we redefine the smallest region of overlap and characterize the clinical features of the 9q31 deletion syndrome.