Pure De Novo 4.5 Mb Duplication at Xp11.22-p11.23 in an 18-Month-Old Boy: Phenotypic and Molecular Characterization

Objective − The aim of this study was the molecular characterization of a very rare de-novo 4.5 Mb duplication at Xp11.22-p11.23 in an 18-month-old boy with hypotonia and developmental delay, and to correlate these findings with a clinical phenotype and to expand the knowledge of this genetic abnormality. Case Report − The patient is unable to utilize the large muscle systems to move from place to place, assume a stable posture when moving, and to raise himself to a standing position. He is incapable of coherent speech. Single nucleotide polymorphism (SNP) was performed using the Affymetrics Cytoscan High Density platform and maternal fluorescence in situ hybridization (FISH) analysis was used to determine the inheritance pattern. Chromosome microarray test found Xp11.23-p11.22 (48,237,630-52, 737, 268) x2 including numerous OMIM genes (start: SSX4 to end: SSX7) and SHROOM4. Maternal FISH analysis did not detect duplication of Xp11.23. Conclusion − This is de novo change in our patient most likely occurred as a new mutation that was not inherited from either parent.