RESUMO
Aims: To report a case of ring chromosome 13 in a female child. Presentation of Case: Female, Caucasian, born in Southeast of Brazil, 6 years old. Born by cesarean section, the physical examination at 6 years and 1 month old has shown: weight of 19.100 grams and 105 centimeters tall, developmental delay, bushy eyebrows, epicanthic folds and broad nasal bridge, cardiovascular and respiratory systems were normal and no abnormalities in the limbs. Chromosome analysis was performed by GTG banding of peripheral blood and the karyotype was 46,XX,r(13)(p13q34)[97]/46,XX,dic r(13;13)(p13q34;p13q34) [3]. Analysis of 100 metaphases following G-banding revealed 97% cells with a ring chromosome 13,3% with dicentric ring chromosome of two 13s. Aneuploidy was not detected. Her parents had a normal karyotype. Discussion: Some researchers relate the clinical presentation of ring chromosome 13 with the extension of the deleted chromosomal region and instability. Others suggested that phenotypes of patients can be categorized in groups, according to the breakpoint on 13q. Conclusion: The classification of cases in groups based on breakpoints and chromosomal instability is still inaccurate, with variable phenotypes. Thus, the analysis of a greater number of cases and molecular analysis are important to establish more precise correlation between genotype and phenotype.