RESUMO
OBJECTIVES: Ring chromosomes, which are formed through the fusion of the telomeric ends of a chromosome, present with a spectrum of symptoms whose severity depends on the amount of genetic material lost. Ring chromosome 13 cases present with symptoms similar to that of deletion 13q syndrome, and can be classified depending on whether several critical regions are involved in the deletion. An important region to consider is locus 13q32, whose deletion is known to cause severe phenotypes and major malformations. In contrast, deletions of the more distal locus 13q34 have been shown to be involved in symptoms such as microcephaly and ambiguous genitalia. Herein, we report a case of a pediatric patient with r(13) who presented with microcephaly, facial dysmorphism, hand and feet anomalies, and ambiguous genitalia. The karyotype was described as 46,XY,r(13)(p11.1q34). This case highlights the importance of cytogenetic analysis in determining the prognostic implications of ring chromosome cases.