ABSTRACT
Objective:To analyze the clinical characteristics and genetic features of SMC1A gene related disorders. Methods:The data of 5 children with SMC1A gene variants were collected from Children′s Hospital of Fudan University from February 2018 to January 2022. The clinical features, electroencephalogram (EEG), brain imaging and gene testing results were summarized. Results:Among the 5 patients, 4 are females and 1 is male. Two female cases are siblings. One boy had dysmorphic features, consisting of bilateral ptosis, synophrys, a short nose and upturned nasal tip. He also had patent foramen ovale plus atrial septal defect, unilateral cryptorchidism and microcephaly. Three cases had microcephaly. Two girls had patent foramen ovale, and 2 girls had microcephaly. Four cases had epilepsy, and age at seizure onset ranged from 2 to 52 months. Multiple seizure types were observed, including bilateral tonic clonic seizures in 2 patients, and focal seizures in 3 patients. The seizures in 3 cases were in cluster. All patients had developmental delay, including 1 patient with mild and 4 patients with moderate to severe developmental delay. Three patients had slow background activity in EEG. Interictal EEG showed abnormal discharges in 4 patients, including focal discharges in 3 cases and generalized discharges in 1 case. Brain magnetic resonance imaging was normal in 3 patients and showed mild cortical thickening in 1 case. All cases harbored 4 SMC1A gene variants, including 2 missense variants and 2 frameshift variants (c.580_587del, c.2699delG, c.3362G>A, c.1486C>T). Three cases harbored heterozygous SMC1A variants and 2 cases carried somatic mosaic SMC1A variants with 17.5% and 88.1% mosaicism in peripheral blood. The follow-up lasted for 3 months to 4 years. The epilepsy was refractory in 2 cases. During the follow-up, all cases had very slow developmental progress or developmental retardation. All cases had different levels of growth retardation. The scores of Cornelia de Lange syndrome (CdLS) phenotypes in 5 cases were 2-6. One case had the combined phenotypes of atypical CdLS and developmental epileptic encephalopathy (DEE). The phenotype was atypical CdLS in 1 case and DEE in 1 case. The phenotypes of 2 cases with SMC1A missense variants were mild, manifesting as non-refractory epilepsy and moderate to severe developmental delay. Conclusions:All of cases with SMC1A gene variants have developmental delay. Most of the patients have clusters of seizures and some dysmorphisms. The phenotypes of SMC1A gene related disorders are diverse. Except CdLS and DEE, there are some patients with mild phenotype due to missense variants of SMC1A gene.
ABSTRACT
Objective:To explore the characteristics, clinical manifestations and gene mutation types of Cornelia de Lange syndrome (CdLs), and to improve the understanding of the disease.Methods:Clinical data and gene test results of a pediatric case of CdLs diagnosed in the First Affiliated Hospital of Xinxiang Medical University in August 2019 were analyzed retrospectively.Results:A female patient with 2 years and 8 months old presented a special appearance with a low and flat nose, a wide eye distance, audition ears, a downward inclination of the mouth corner, a high arch of the jaw and a small jaw deformity, who had recurrent seizures, speech and mental retardation.The result of gene test showed the mutation of SMC1A gene c. 2923C > T, and thus the patient was diagnosed as type 2 CdLs. Conclusions:CdLs is a rare genetic metabolic disease with special facial features and physical signs.There is only one case of CdLs with gene mutation of SMC1A in China through literature review.The mutation of SMC1A gene c. 2923C>T in CdLs cases has not been reported at home and abroad, which expands the variation spectrum of the SMC1A gene.