Chromosome 12q14 deletions and review of the literature

chromosome 12

Chromosome 12q14 deletions and review of the literature to determine the identification of relevant disease causing genes in these patients.

Deletions of 12q14 are relatively well known. The authors report two boys with non-overlapping deletions in this area. The first one with a 4.4 Mb deletion in 12q14.2q15 had short stature, mild developmental delay, café-au-lait spot and a slightly dysmorphic face. The second boy with a 7.3 Mb deletion in 12q13.2q14.2 had severe delay in psychomotor development, a coarse dysmorphic face, a ventricular septal defect, dislocations of the hips and knees, flexor contractures and syndactyly of 2-3 toes. An analysis of previously published patients with deletions in this area allowed a proposition of the existence of several clusters within the long arm of chromosome 12. Cluster 1 includes several patients with deletions of the paracentromeric area of the long arm 12q. Cluster 2 includes patients who lost the SMARCC2 and KIF5A genes. The authors’ patient 2 fits into this cluster. The authors suggest that the involvement of the SMARCC2 gene explains more severe manifestations. Cluster 3 involved mainly the 12q14.3 segment. The authors’ patient 1 (as well as more than 20 previously reported patients) fits into this group. The main player for these patients is the HMGA2 gene. Clusters 4 and 5 involve patients with more distal deletions (mainly 12q21 for cluster 4 and 12q24 for cluster 5). According to the authors the subdivision of all deletions in 12q into several clusters allows the identification of relevant disease causing genes in these patients.

Deng R. et al. “Case report: two new cases of chromosome 12q14 deletions and review of the literature”. “Frontiers in Genetics” 2021, v. 12:716874.