Ring Chromosome 13

Ring chromosome 13 (RC13) is detected using karyotyping, fluorescence in situ hybridization (FISH), and chromosome microarray analysis (CMA) to define its ring structure, dynamic mosaicism, and associated genomic imbalances. Patients with a RC13 showed microcephaly, craniofacial dysmorphisms, intellectual disability, developmental delay, hand and foot hypoplasia, anorectal and skeletal anomalies, delayed speech, hearing loss, and malformations in the brain, heart, eyes, and kidneys. Prenatal diagnosis of RC13 and genetic counseling is effective for an informative decision on elected termination of pregnancy. Almost all reported pediatric and adult cases of RC13 occur de novo except for one case of a mother-to-daughter transmission and another case of consecutive pregnancies of a RC13 likely resulted from maternal germline mosaicism. Exploring genomic imbalances for genotype–phenotype correlations could provide valuable insights into clinical manifestations in patients of RC13. Thorough examinations by clinical geneticists and referrals to specialists in neurology, cardiology, otolaryngology, ophthalmology, and oncology should be considered based on clinical features in the patients of RC13.