17q243

17q243, typically written as 17q24.3 in cytogenetic nomenclature, refers to a band on the long arm (q) of chromosome 17. Cytoband designations like 17q24.3 describe a defined region used in genetic testing and reporting. The exact base-pair coordinates of this band vary between genome assemblies (for example GRCh37 and GRCh38), but the band sits in the mid to distal portion of the long arm of chromosome 17 and is analyzed in both research and clinical diagnostics as part of the 17q region.

A key gene located in this region is SOX9, a transcription factor essential for chondrogenesis and skeletal development. SOX9 lies within 17q24.3 and is a well-established contributor to human disease. Pathogenic variants affecting SOX9 cause campomelic dysplasia and can also lead to sex development disorders in individuals with XY karyotypes. Because SOX9 is within this band, copy number variations that disrupt or alter the expression of genes in 17q24.3 can have clinical consequences. The region contains multiple other genes as well, and the phenotype associated with a CNV in 17q24.3 depends on the specific gene content and the size of the rearrangement.

In clinical genetics, 17q24.3 is evaluated using molecular cytogenetic and genomic techniques such as array-based comparative genomic hybridization or SNP microarrays, as well as targeted sequencing or fluorescence in situ hybridization when specific abnormalities are suspected. Abnormalities in this region are associated with a spectrum of developmental and skeletal phenotypes, with the precise presentation reflecting the affected genes. See also chromosome 17 and SOX9.