Clinical and genetic characteristics and prenatal diagnosis of patients presented GDD/ID with rare monogenic causes
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RESEARCH
Clinical and genetic characteristics and prenatal diagnosis of patients presented GDD/ID with rare monogenic causes Liling Lin1, Ying Zhang1, Hong Pan1, Jingmin Wang2, Yu Qi1 and Yinan Ma1*
Abstract Background: Global developmental delay/intellectual disability (GDD/ID), used to be named as mental retardation (MR), is one of the most common phenotypes in neurogenetic diseases. In this study, we described the diagnostic courses, clinical and genetic characteristics and prenatal diagnosis of a cohort with patients presented GDD/ID with monogenic causes, from the perspective of a tertiary genetic counseling and prenatal diagnostic center. Method: We retrospectively analyzed the diagnostic courses, clinical characteristics, and genetic spectrum of patients presented GDD/ID with rare monogenic causes. We also conducted a follow-up study on prenatal diagnosis in these families. Pathogenicity of variants was interpreted by molecular geneticists and clinicians according to the guidelines of the American College of Medical Genetics and Genomics (ACMG). Results: Among 81 patients with GDD/ID caused by rare monogenic variants it often took 0.5–4.5 years and 2–8 referrals to obtain genetic diagnoses. Devlopmental delay typically occurred before 3 years of age, and patients usually presented severe to profound GDD/ID. The most common co-existing conditions were epilepsy (58%), microcephaly (21%) and facial anomalies (17%). In total, 111 pathogenic variants were found in 62 different genes among the 81 pedigrees, and 56 variants were novel. The most common inheritance patterns in this outbred Chinese population were autosomal dominant (AD; 47%), following autosomal recessive (AR; 37%), and X-linked (XL; 16%). SCN2A, SHANK3 and STXBP1 were important causal genes. Hot-spot variants were rarely found. By the follow-up, 33 affected families, including 15, 13 and 5 families inherited in AR, AD and XL modes respectively, had undergone prenatal diagnosis. And the recurrence rates are 26.7%, 15.4% and 20% for families inherited in AR, AD, and XL patterns. Conclusion: Patients presented with GDD/ID caused by rare single gene variants are characterized by early onset, relatively severe symptoms and great clinical variability and genetic heterogeneity. Timely referrals to genetic counseling and prenatal diagnostic laboratories are important for affected families planning to have additional children. Keywords: Global developmental delay and intellectual disability (GDD/ID), Monogenic disease, Prenatal diagnosis, Next-generation sequencing
*Correspondence: [email protected] 1 Department of Central Laboratory, Peking University First Hospital, No. 8, Xishiku Street, Xicheng District, Beijing 100034, China Full list of author information is available at the end of the article
Introduction Global developmental delay/intellectual disability (GDD/ID), used to be named as mental retardation (MR) is one of the most common phenotypes in neurogenetic diseases. Global developmental delay (GDD), is characterized by a del
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