The syndrome of ring chromosome 12

Abstract

We have studied a 13 month-old girl with failure to thrive developmental delay, and dysmorphic features. At 13 months, the weight-age was 1 month, length-age was 3 months and head circumference was at the 3rd centile for 3 months. Physical findings were: Epicanthal folds, mildly cupped, apparently low-set ears, highly arched palate, short neck with low hairline, clinodactyly, and single crease of left 5th finger. The modal chromosome number was 46. Trypsin-G banding identified a ring chromosome 12; Karyotype was 46,XX,r(12)(p13q24).

De novo deletion 12q: Report of a patient with 12q24.31q24.33 deletion

“…Four patients with ring chromosome 12 have been described [Hamerton et al, 1973;Scribanu et al, 1980;Zuffardi et al, 1980;Park et al, 1988]. No characteristic phenotype has been delineated for these cases, and by description, the phenotypic findings were different from those observed in our patient.…”

“…Rearrangements resulting in loss of chromosomal material from 12q include translocations [Hustinx et al, 1975;Angulo et al, 1984;Masuno et al 1995;Elbistan et al, 1994] and ring chromosome 12 [Hamerton et al, 1973;Scribanu et al, 1980;Zuffardi et al, 1980;Park et al, 1988]. We report on a patient with a de novo interstitial 12q deletion that has not been described previously.…”

Esophageal and duodenal atresia in a girl with a 12q24.3‐qter deletion

“…Some patients with deletions (1–4) or de novo translocations involving the distal part of the long arm of chromosome 12 have been described (5–8) but the breakpoints were more proximal than in our case and their phenotypes were different. Four patients with ring chromosome 12 have been reported (6, 9–11) but no characteristic phenotype was delineated and none of these patients was similar to ours. More interestingly, Sathya et al.…”

Ultrasonographic Prenatal Diagnosis of the 13q-Syndrome

“…The clinical severity, however. is greater when a ring chromosome is in volved than when there is a partial deletion of the same chromosome [5], This is most likely due to the fact that a ring chromosome is essentially an unstable rearrangement prone to mechanical difficulties at the time of DNA replication and chromosome movement. During mitosis, a ring chromosome ideally generates two identical ring chromosomes which are then distributed to two daughter nuclei.…”