A Turner Patient Presenting Dicentric Ring X-Chromosome and Intellectual Disability

A ring chromosome is the result of fusion of the proximal ends following a break in both arms of a chromosome. Formation of a dicentric ring which is a rare event occurs as a consequence of either U-type exchange or due to misrepair of the DNA strand breaks. The proband in our study clinically presented as Turner syndrome with intellectual disability. Chromosomal analysis revealed her karyotype to be 45,X[50]/46,X,r(X) (p11q13)[30]/46,X,dic r(X;X)(p11q13;p11q13) [20] which was further confirmed using specialized banding techniques and fluorescence in situ hybridization. Intellectual disability in our patient could have been due to the active ring X chromosome. To the best of our knowledge this is the first case of a stable dicentric ring X chromosome associated with both Turner syndrome and intellectual disability. This report describes the genotypic and phenotypic features exhibited by the patient.