Case Report of Ring Chromosome 13: 46,xx.r(13)(p13q34)/46,xx,dicr(13;13)(p13q34;p13q34).

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.

Phenotypical characterization of 13q deletion syndrome: Report of two cases.

Patients with 13q deletion syndrome are characterized with different phenotypical features depending on the size and location of the deleted region on chromosome 13. These patients fall into three groups: In Group 1, deleted region is in the proximal and does not extend into q32; in Group 2, deleted region involves proximal to the q32 and in Group 3 q33‑q34 is deleted. We present two cases with 13q syndrome with two different deleted region and different severity on clinical features: One case with interstitial deletion belongs to the Group 1 with mild mental retardation and minor malformations and the other case with terminal deletion belongs to Group 3 with moderate to severe mental retardation and major malformations.

A Rare Case of a de novo Proximal Deletion of 13q in a Neonate with Congenital Megacolon

Chromosome 13q deletion syndrome, which is relatively rare, is characterized by a wide spectrum of phenotypes resulting from a partial deletion of the long arm of the chromosome 13. The main clinical features are mental retardation, developmental delay, craniofacial dysmorphism, and various congenital defects. Here, we report a de novo interstitial deletion in chromosome 13 (q21.3q31) in a neonate with congenital megacolon (Hirschsprung disease) confirmed by biopsy. A short tandem repeat analysis (D13S317) was used to compare the loci on the chromosomes of the patient and the parents, the latter representing the normal karyotype, to determine how the features of the profile peaks relate to the deletion. The clinical data were also compared with those of similar cases in previously published reports.