Abstract
SMC1A encodes one of the proteins of the cohesin complex. SMC1A variants are known to cause a phenotype resembling Cornelia de Lange syndrome (CdLS). Exome sequencing has allowed recognizing SMC1A variants in individuals with encephalopathy with epilepsy who do not resemble CdLS. We performed an international, interdisciplinary study on 51 individuals with SMC1A variants for physical and behavioral characteristics, and compare results to those in 67 individuals with NIPBL variants. For the Netherlands all known individuals with SMC1A variants were studied, both with and without CdLS phenotype. Individuals with SMC1A variants can resemble CdLS, but manifestations are less marked compared to individuals with NIPBL variants: growth is less disturbed, facial signs are less marked (except for periocular signs and thin upper vermillion), there are no major limb anomalies, and they have a higher level of cognitive and adaptive functioning. Self-injurious behavior is more frequent and more severe in the NIPBL group. In the Dutch group 5 of 13 individuals (all females) had a phenotype that shows a remarkable resemblance to Rett syndrome: epileptic encephalopathy, severe or profound intellectual disability, stereotypic movements, and (in some) regression. Their missense, nonsense, and frameshift mutations are evenly spread over the gene. We conclude that SMC1A variants can result in a phenotype resembling CdLS and a phenotype resembling Rett syndrome. Resemblances between the SMC1A group and the NIPBL group suggest that a disturbed cohesin function contributes to the phenotype, but differences between these groups may also be explained by other underlying mechanisms such as moonlighting of the cohesin genes.
| Original language | English |
|---|---|
| Journal | American Journal of Medical Genetics, Part A |
| Volume | 173 |
| Issue number | 8 |
| Pages (from-to) | 2108-2125 |
| Number of pages | 18 |
| ISSN | 1552-4825 |
| DOIs | |
| Publication status | Published - 08.2017 |
Funding
We are exceptionally grateful to the patients with SMC1A variants and their families who participated in this study. We are very grateful to the Prinsenstichting for funding in part the work of SH, and to the Dutch and Polish CdLS Associations for cooperation in the development of detailed clinical data NIPBL positive patients. We sincerely thank Dr Alina Kuzniacka and Natalia Krawczy?ska from Department of Biology and Genetics, Medical University in Gda?sk for molecular analysis. This work was supported by National Institutes of Health Grants UMO-2014/15/B/NZ5/03503. This work was supported by the Spanish Ministry of Health ? ISCIII, Fondo de Investigaci?n Sanitaria (FIS) [Ref: PI15/00707] and the Diputaci?n General de Arag?n [Grupo Consolidado B20], European Social Fund (?Construyendo Europa desde Arag?n?) to FJRF and JPJ. This work was funded by the German Federal Ministry of Education and Research (BMBF, CHROMATIN-Net) to FJK and GG-K. We dedicate this manuscript to the excellent clinician and caregiver, a colleague and a friend, Ton van Essen, who died during the preparation of the manuscript.
Research Areas and Centers
- Research Area: Medical Genetics
DFG Research Classification Scheme
- 2.22-03 Human Genetics