Resumo

PASKULIN, Giorgio Adriano et al. Importance of the fibroblast chromosomal analysis in suspected cases of mosaicism: experience of a clinical Genetics service. Rev. paul. pediatr. [online]. 2011, vol.29, n.1, pp. 73-79. ISSN 0103-0582.  http://dx.doi.org/10.1590/S0103-05822011000100012.

OBJECTIVE: To verify clinical characteristics and cytogenetic findings of patients suspects of having mosaicism and submitted to chromosomal analysis of lymphocytes and fibroblasts through GTG-Banding karyotype. METHODS: This is a retrospective analysis of the patients evaluated in the Genetic Clinic of Complexo Hospitalar Santa Casa de Porto Alegre of the Universidade Federal de Ciências da Saúde de Porto Alegre, from 1975 to 2009 (clinical data and results of cytogenetic exams were evaluated). RESULTS: Fifteen patients were enrolled, being six males (40%) with ten days to 14 years-old. Alterations in the chromosomal analysis of blood were observed in four patients (26.7%) and included one case of balanced translocation [t(2;9)pat] and three cases of mosaicism [mos 45,X/46,X,+mar; mos 46,XY,r(12)/45,XY,-12/47,XY,r(12),+r(12) and mos 46,XY/47,XY,+9]. The patients were then submitted to skin karyotype to confirm or to identify a chromosomal mosaicism. The main reasons for such suspicion in patients with blood karyotype without mosaicism were the presence of hemihypertrophy (n=5) and skin spots following the Blaschko lines (n=4). Mosaicism was confirmed in two cases and identified in another two (two cases of mos 46,XX/47,XX,+22). The mos 46,XY/47,XY,+9 was not verified in the fibroblast study. CONCLUSIONS: Our results highlight the tissue variability that is characteristic of chromosomal mosaicism, as well as confirm the importance of the evaluation of a second tissue for the diagnosis. Clinical findings, as limb asymmetry and pigmentary anomalies following the Blaschko lines, are strongly indicative of mosaicism.

Palavras-chave : mosaicism; chromosome aberrations; cytogenetic analysis; pigmentation disorders; hypertrophy.