Novel rearrangements between different chromosomes with direct impact on the diagnosis of 5p- syndrome

ABSTRACT

Abstract Objectives Copy Number Variations (CNVs) in the human genome account for common populational variations but can also be responsible for genetic syndromes depending on the affected region. Although a deletion in 5p is responsible for a syndrome with highly recognizable phenotypical features, other chromosomal abnormalities might overlap phenotypes, especially considering that most studies in 5p use traditional cytogenetic techniques and not molecular techniques. Methods The authors have investigated 29 patients with clinical suspicion of 5p- syndrome using Chromosomal Microarray (CMA), and have gathered information on previous tests, clinical signs, symptoms, and development of the patients. Results The results showed 23 pure terminal deletions, one interstitial deletion, one deletion followed by a 3 Mb duplication in 5p, three cases of 5p deletion concomitant to duplications larger than 20 Mb in chromosomes 2, 9, and 18, and one 5p deletion with a chromosome Y deletion. CMA showed relevant CNVs not typically associated with 5p- that may have contributed to the final phenotype in these patients. Conclusions The authors have identified three novel rearrangements between chromosomes 5 and 2 (Patient 27), 5 and 18 (Patient 11), and 5 and Y (Patient 22), with breakpoints and overlapped phenotypes that were not previously described. The authors also highlight the need for further molecular investigation using CMA, in different chromosomes beyond chromosome 5 (since those cases did not show only the typical deletion expected for the 5p- syndrome) to explain discordant chromosomal features and overlapped phenotypes to unravel the cause of the syndrome in atypical cases. HIGHLIGHTS The authors The authors have described three novel rearrangements between chromosomes 5 and 2, 5 and 18, and 5 and Y with chromosomal breakpoints and overlapped phenotypes that were not previously described. One of the main atypical features for 5p- syndrome that the authors report was the presence of seizures that was found in the three patients with rearrangements between different chromosomes and in a patient with a deletion followed by duplication in 5p. The authors suggest physicians conduct further molecular investigation in the presence of atypical clinical features for patients with 5p- syndrome suspicion.