Higher CNV Frequencies in Chromosome 14 of Girls With Turner Syndrome Phenotype

Abstract

Abstract Context Precise genotype-phenotype correlations in Turner syndrome (TS) have not yet been deciphered. The chromosomal basis of the clinical TS phenotype in the absence of X chromosome aberrations on conventional karyotyping remains more and less unexplored. Objective To elucidate the high-resolution chromosomal picture and analyze the genotype-phenotype associations in girls with clinical phenotype of TS by chromosomal microarray. Design and Patients Cross sectional observational study conducted between October 2018 and January 2020 on 47 girls presenting the clinical TS phenotype and fulfilling the criteria for chromosomal analysis. Setting Outpatient department at Department of Endocrinology and the Molecular Research Lab at tertiary care teaching institution. Results The copy number variation (CNV) polymorphs were more frequent on autosomes than X chromosomes, and they were detected in 89.3%, 61.7%, and 92.8% of patients, respectively, on chromosome 14 or X or both. A total 445 and 64 CNV polymorphs were discovered on chromosome X and 14, respectively. The latter exhibited either gain at 14q32.33, loss at 14q11.2, or both. Karyotype was available for 27 patients; 55.6% of cases displayed X chromosome abnormalities while 44.4% cases had a normal karyotype. Functional interactomes of the genes that were present in chromosome 14 CNVs and those known to be associated with TS showed an overlap of 67% and enriched various development-related cellular pathways underlying TS phenotype. Conclusions On high-resolution karyotype analysis, clinical phenotype of TS can be associated with CNV defects in autosomes, specifically chromosome 14 or X chromosome or both. The syndrome of chromosome 14 CNV defects with and without X-chromosomal defects clinically mimics TS and shares a common genomic network that deserves further investigations.