A case of de novo ring (13) chromosome with deletion 13q32.2-->qter

Hwang, Seong Jin; Lee, Jee Hyun; Park, In Yang; Moon, Hee Bong; Oh, Joon Hwan; Lee, Gui Se Ra; Yi, Chong Seung; Shin, Jong Chul; Kim, Soo Pyung

Abstract

We report a case of ring chromosome 13 with a distal deletion of 13q32.2-->qter observed in a fetus who was referred to our institution at term due to severe growth restriction and multiple congenital malformations on ultrasonographic examination.This boy was born by vaginal delivery at 39 weeks in gestation. His weight, head circumference and height were less than the 3 percentile of gestational age. Apgar score was 7 at 1 minute and 9 at 5 minutes. He showed microcephaly, large forehead, low set ears, hypertelorism, flat nasal bridge, and micrognathia. The genitalia was ambiguous, showing severe hypoplasia of the penis. The anus was ectopic, displaced anteriorly from its normal position but with a normal opening and function. Neurologic examination was normal. Echocardiogram done at 2 weeks of life showed a persistent foramen ovale and a ventriculoseptal defect (type II) with increased pulmonary hypertension. MRI examination of the brain showed poorly demarcating corpus callosum suspecting agenesis of corpus callosum. Also, cerebellar vermis was small and hypoplastic, mimicking a variant form of Dandy-Walker malformation. MRI of the pelvis showed a tubular structure in pelvic cavity, suspicious of uterine remnant, between urinary bladder and rectum, and a inguinal hernia was noted in the left side. In the abdominal cavity enlarged adrenal glands were noted, and hormonal study showed elevated 17-alpha-OH-progesterone (168.9 ng/ml) with normal 17-KS and 17-OHCS levels. Gastrointestinal and urogenital system were otherwise normal. Cytogenetic analysis of the parents were both normal but the newborn showed 46, XY, r (13), de novo, with deletion points q32.2-->qter. Our findings are in line with previous reports about chromosome 13 deletions, in which loss of the "critical point" leads to major malformations like brain anomalies and ambiguous genitalia.