engleski

Cytogenetic evaluation, fluorescence in situ hybridization and molecular study of psu idic(X)(pter->q22.3::q22.3->pter) chromosome aberration in a girl with moderate growth retardation

This report points out the usefulness of combined cytogenetic, fluorescence in situ hybridization (FISH), and molecular analysis in the diagnosis of sex chromosome aberrations. The proband was a 4-years old girl with mild dysmorphism and growth retardation. Standard cytogenetic and FISH analysis were done on slides obtained by peripheral blood lymphocytes culture, and the molecular study was performed using DNA polymorphism analysis. Both parents presented with normal karyotypes. Chromosome analysis of the proband identified the karyotype with 46 chromosomes and a late replicating dicentric X. Interphase FISH with an alpha satellite X centromere probe revealed two mosaic cell lines. Three signals were observed in 84.5% and one signal in 15.5% of the interphase cells. Molecular analysis showed that the dicentric was of paternal origin. Based on this study we concluded that the karyotype of the patient was 45, X/46, X, psu idic(X)(q22.3), with the trisomy Xpter--q22.3 and monosomy Xqter--q22.3. Dicentric X was the results of an isolocal break in both chromatids of the paternal X chromosome and subsequent rejoining of broken ends, followed by inactivation of the one centromere. Combined cytogenetic, FISH, and molecular analyses provide a powerful tool to elucidate the mechanism of the chromosomal abnormality formation and establish the diagnosis.

Cytogenetics; FISH; parental origin; replication pattern; dicentric; X chromosome

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