Chromosomal Triple Mosaicism in a Male with Turner Syndrome, 8p21.1–pter Deletion, and Yq Deletion: A First Case Report

Abstract

We present the case of a male patient who was under medical observation as an infant due to cardiac malformations, microcephaly, dysmorphic features, and psychomotor developmental delay. Karyotyping revealed mosaicism for Turner syndrome and a deletion of the short arm of chromosome 8 (8p-). Fourteen years later, the patient developed refractory epilepsy, and the case was re-evaluated with molecular analysis to delineate the 8p deletion. This analysis broadened the scope of the loss and also detected an additional cell line exhibiting mosaicism with a partial loss of the long arm of the Y chromosome (Yq-), resulting in a mosaicism for three chromosomal abnormalities. However, the molecular technique was limited in its ability to identify that one of the cell lines contained X monosomy and the 8p- deletion. A new karyotype was subsequently performed, confirming the findings of the initial analysis. The patient's phenotype is described, and genotype-phenotype correlations are established, along with the influence and possible origins of structural and numerical chromosomal alterations on the patient's clinical presentation. This first case with these alterations in the same patient demonstrates the importance of complementary analytical techniques and the ideal future goal of routinely implementing simultaneous genetic analyses with complementary tests to improve our understanding of the genome and its potential alterations.