Cytogenomic investigation in patients with global development delay and pigmentary mosaicism

• Grant number: 18/20936-4
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Effective date (Start): January 01, 2019
• Effective date (End): December 31, 2022
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Leslie Domenici Kulikowski
• Grantee: Yanca Gasparini de Oliveira
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Mosaicism is a relatively frequent phenomenon in the general population, and presents a comprehensive clinical phenotype. In the literature, it is described the pigmentary mosaicism is a term that describes varied patterns of skin pigmentation caused by genetic heterogeneity of skin cells. In a substantial number of cases, pigmentary mosaicism is seen alongside extra cutaneous abnormalities typically involving the central nervous system and the musculoskeletal system, and the presence of pigmentary skin spots in patients with intellectual disability, facial dimorphisms and overall developmental delay are frequently reported. This variety of phenotypes is related to the percentage of mosaicism present in the same individual, either in the same tissue or in different tissues, and this percentage is responsible for minimizing clinical phenotypes that, in a non-mosaic state, could be more comprehensive. This will depend on the type of genomic change, the tissue of origin and the period of development in which a new cell line arose. Mosaicism may result from different mechanisms, including non-chromosome disjunction, delay anaphase, endoreplication, and genetic mutations that occurred during development. The mosaicism can be identified cytogenetically, however the simultaneous molecular characterization or in distinct tissues still presents a challenge. Therefore, our study will investigate the presence of cytogenetic changes s in saliva, blood and skin samples from 20 patients with global developmental delay and pigmentary mosaicism to have better understand the mechanisms of appearance of these abnormalities, as well as their association with the clinical consequences. (AU)