Subtelomeric rearrangements in patients with idiopathic intellectual disabilitiy/ multiple congenital anomalies and recurrent miscarriages: seven years' experience.

Cryptic subtelomeric anomalies are a significant cause of idiopathic intellectual disability and/or multiple congenital anomalies (ID/MCA) and multiple miscarriages (MM). Effective preselection of patients is essential as the cost of subtelomeric testing is high and it is labor-intensive. Therefore, the aim of this study is to evaluate the frequency of subtelomeric anomalies by using commercial FISH probes in 151 patients of ID/MCA and 32 couples with MM who were referred to a genetic center during 7-year period and to determine whether performing subtelomeric testing is feasible for these groups of patients. We assessed the clinical information of all referrals including family history, physical examination, facial dysmorphism, congenital malformations and scored the ID/MCA patients according to the criteria suggested previously. The etiology was not elucidated and all patients had normal karyotypes. Subtelomeric deletions were found in 10 patients in ID/MCA group (6.62%). These were deletions of 14qter (2 patients), 18qter (2 patients), 18pter (2 patients), 15qter, 7pter, 8pter and 4qter. The clinical information of all patients having deletions has been summarized and confined with the current literature. No anomaly was detected in the MM group. In conclusion, the prevalence of subtelomeric anomalies in ID/MCA group in this study is consistent with the literature and subtelomeric FISH analysis is feasible in determining their etiology when a checklist is used. Besides, assessment of the genetic basis of ID/MCA had lead the prevention of the recurrence of such conditions in selected families as well as elucidating novel genetic causes of ID.