Delineation of the 1q24.3 microdeletion syndrome provides further evidence for the potential role of non-coding RNAs in regulating the skeletal phenotype.

Microdeletions within 1q24 have been associated with growth deficiency, varying intellectual disability, and skeletal abnormalities. The candidate locus responsible for the various phenotypic features of this syndrome has previously been predicted to lie in the area of 1q24.3, but molecular evidence of the causative gene remains elusive. Here, we report two additional patients carrying the smallest reported 1q24 deletion to date. Patient 1 exhibited intrauterine growth retardation, shortening of the long bones, frontal bossing, microstomia, micrognathia, and a language acquisition delay. Her mother, Patient 2, displayed a broad forehead and nasal bridge, thick supraorbital ridges, and toe brachydactyly, along with learning disability and language acquisition delay. The microdeletion encompasses a 94 Kb region containing exon 14 and portions of the surrounding introns of the gene encoding dynamin 3 (DNM3), resulting in an in-frame loss of 38 amino acids. This microdeletion site also contains a long non-coding RNA (DNM3OS) and three microRNAs (miR-214, miR-199A2, and miR-3120). Following culture of patient-derived and control fibroblasts, molecular analyses were performed to determine expression levels of genes affected by the heterozygous deletion. Results show decreased expression of DNM3OS and miR-214-3p in patient fibroblasts cultured in an osteogenic induction medium. Overall, our data provide further evidence to support a functional role for non-coding RNAs in regulating the skeletal phenotype, and the potential of a functionally-impaired DNM3 protein causing the non-skeletal disease pathogenesis.