Twenty-year cytogenetic and molecular follow-up of a patient with ring chromosome 15: a case report

INTRODUCTION Ring chromosome 15 is a rare disorder, with only a few over 40 cases reported in the literature. There are only two previous reports of cases where patients with ring chromosome 15 have been followed-up. CASE PRESENTATION We report here on the 20-year clinical and cytogenetic follow-up of a patient with a ring chromosome 15. Our patient, a Caucasoid Asian woman, presented with short stature, microcephaly, minor dysmorphic features, hyperextensible knees, generalized hirsutism, café-au-lait and small hypochromic spots spread over her face and the front of her chest and abdomen, dorsolumbar scoliosis and mild intellectual disability. She was followed-up from the age of eight to 28 years. When she was 27 years old, she was reported by her mother to present with compulsive overeating and an aggressive mood when challenged. Karyotyping revealed that the majority of her cells harbored one normal chromosome and one ring chromosome. Silver staining revealed the presence of the nucleolar organizer region in the ring chromosome. Ring loss and/or secondary aberrations exhibited a slight increase over time, from 4.67% in 1989 to 7.67% in 2009, with the presence of two monocentric rings, cells with interlocked rings, a dicentric ring, and broken or open rings. A genome-wide array technique detected a 5.5Mb deletion in 15q26.2. CONCLUSIONS We observed that some phenotypic alterations in our patient can be associated with gene loss and haploinsufficiency. Other features may be related to different factors, including ring instability and epigenetic factors.