OBJECTIVE: To explore the clinical phenotype and genetic etiology of a child with Ehlers-Danlos syndrome, spondylodysplastic type 2 (EDSSPD2). METHODS: A child who was admitted to the Children's Medical Center of the Affiliated Hospital of Guangdong Medical University in July 2024 for "delayed motor development for 1 and a half year" was selected as the study subject. Clinical data of the child was collected, including medical history, family history, and results of auxiliary examinations. Peripheral venous blood samples were collected from the child and his two brothers and both parents. Genomic DNA was extracted from the child and his family members and subjected to whole-exome sequencing (WES) and copy number variation (CNV) analysis. Sanger sequencing was used to verify the parental origin of the candidate variants. Multiple protein function prediction software tools, including SIFT, PolyPhen-2, and REVEL, were used to assess the impact of candidate variants on the protein function. Based on protein database information from UniProt, a two dimensional structural schematic of the target protein was generated. The pathogenicity of the variants was classified based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). Relevant literature on the B3GALT6 gene variants leading to EDSSPD2 was retrieved from CNKI, Wanfang Data Knowledge Service Platform, and PubMed databases. The procedures followed in this study were reviewed and approved by the Medical Ethics Committee of Affiliated Hospital of Guangdong Medical University (Ethics No.：PJ2021-097). RESULTS: The proband was a 2-year-old male with an onset in infancy. The main clinical manifestations included loose skin, scoliosis and kyphosis, generalized hypermobility of joints, and motor developmental delay. WES has revealed two compound heterozygous variants of the B3GALT6 gene (NM_080605.4): c.766C>T (p.Arg256Trp) and c.962G>A (p.Cys321Tyr). Sanger sequencing verification showed that the c.766C>T and c.962G>A variants were respectively derived from his phenotypically normal father and mother. Bioinformatics analysis showed that for the c.766C>T (p.Arg256Trp) variant, the Arg256 site is located within the galactosyltransferase catalytic domain (GalT domain) of the β3GalT6 protein. According to the ACMG guidelines, the c.766C>T variant was classified as a likely pathogenic (PS3+PM2_supporting+PM3+PP3), and the c.962G>A was classified as a variant of unknown significance (PM2_Supporting+PM3+PP3). By following the pre-set literature retrieval strategy, a total of 12 articles related to B3GALT6 gene variants were identified (11 English and 1 Chinese), which involved a total of 71 patients. Among these, 4 reports (involving 20 patients) involved B3GALT6 gene variants leading to EDSSPD2. Among the 18 live-born EDSSPD2 patients (including the proband in this study), common clinical manifestations have included scoliosis (88.9%, 16/18), generalized hypotonia (83.3%, 15/18), and soft and lax skin (66.7%, 12/18). Some patients already showed skeletal abnormalities on prenatal ultrasound scan (22.2%, 4/18), while a few presented with cervical instability (16.7%, 3/18). One child had deceased at 18 months of age due to hypoxia caused by tracheomalacia and tracheal compression due to scoliosis. Among the 23 reported EDSSPD2 related B3GALT6 variant sites, missense variants were the most common (78.3%, 18/23), followed by nonsense variants (21.7%, 5/23). CONCLUSION Above finding has enriched the clinical and mutational spectra of EDSSPD2. Early genetic testing has important clinical value for the diagnosis, differential diagnosis, and genetic counseling of this disease.
Humans ; Male ; Ehlers-Danlos Syndrome/genetics* ; Pedigree ; N-Acetylgalactosaminyltransferases/genetics* ; Asian People/genetics* ; DNA Copy Number Variations ; Exome Sequencing ; Female ; Child ; Child, Preschool ; Phenotype ; Mutation ; China ; East Asian People ; Galactosyltransferases

[摘 要] 目的：采用基于中国人群单核苷酸多态性位点开发的同源重组缺陷（HRD）检测工具评估云南地区卵巢癌患者的HRD状态和BRCA1/2基因突变频率并探讨其临床意义。方法：共纳入2021年1月至2023年5月间在云南省肿瘤医院收治的卵巢癌患者248例，HRD状态采用基因组瘢痕评分法（GSS）（主要依据拷贝数的长度、类型、位置及基因组断片）或HRD评分法（杂合性缺失、端粒等位基因失衡及大片段移位等基因组不稳定事件的总和）进行评估，当组织样本的GSS≥50分或HRD评分≥42分者或检测到有害的BRCA1/2基因突变时HRD被定义为阳性。分析患者HRD状态与临床病理特征的关系。结果：248名卵巢癌患者中70.97%的患者HRD呈阳性，其中BRCA1/2基因突变率为30.65%。Ⅲ~Ⅵ期、高级别浆液腺癌的卵巢癌患者具有更高的HRD阳性率（均P<0.01），HRD评分更高的患者其合并其他基因突变的频率也越高（P<0.05）。HRD状态与卵巢癌的病理类型、临床分期和其他基因突变均有关联（均P<0.01）。结论：云南地区卵巢癌患者HRD阳性率较高，HRD阳性的卵巢癌患者可以从聚ADP核糖聚合酶（PARP）抑制剂治疗中获得更大的收益。