简介:尽管在面肩肱骨营养不良(FSHD)的研究中取得了进展,疾病的广泛异质性使其诊断以及患者之间和家庭内部的基因型-表型相关性复杂化.在这种情况下,目前的工作采用全外显子组测序(WES)来调查已知和未知的遗传贡献者,可能参与FSHD,并可能代表潜在的疾病修饰,即使存在D4Z4减少的等位基因(DRA)。方法:研究包括126例FSHD临床体征患者,以D4Z4上浆为特征,甲基化分析和WES。具体方案用于D4Z4大小和甲基化分析,而Illumina®Next-Seq550系统用于WES。该研究包括具有与FSHD诊断相容的DRA的患者和具有较长D4Z4等位基因的患者。如果患者携带来自WES的相关变异,分子分析扩展到家庭成员。结果:WES数据分析突出显示了20种相关变体,其中14个位于已知的遗传修饰基因(SMCHD1、DNMT3B和LRIF1),6个位于候选基因(CTCF,DNMT1,DNMT3A,EZH2和SUV39H1)。它们中的大多数与允许的短(4-7RU)或边界/长DRA(8-20RU)一起发现,支持在FSHD允许背景下,不同基因可能导致疾病异质性的可能性。家庭成员之间的分离和甲基化分析,连同临床发现,提供了更全面的患者图片。讨论:我们的结果支持FSHD病理机制复杂,有几个已知的多基因贡献(SMCHD1,DNMT3B,LRIF1)和可能的其他候选基因(CTCF,DNMT1,DNMT3A,EZH2,SUV39H1)对疾病的外显率和表现力。我们的结果进一步强调了在先证者家族中扩展分子发现分析的重要性,目的是为了解单个病例提供更广泛的框架,并在受FSHD影响的家庭中允许更精细的基因型-表型相关性。
Introduction: Despite the progress made in the study of Facioscapulohumeral Dystrophy (FSHD), the wide heterogeneity of disease complicates its diagnosis and the genotype-phenotype correlation among patients and within families. In this context, the present work employed Whole Exome Sequencing (WES) to investigate known and unknown genetic contributors that may be involved in FSHD and may represent potential disease modifiers, even in presence of a
D4Z4 Reduced Allele (DRA). Methods: A cohort of 126 patients with clinical signs of FSHD were included in the study, which were characterized by
D4Z4 sizing, methylation analysis and WES. Specific protocols were employed for
D4Z4 sizing and methylation analysis, whereas the Illumina® Next-Seq 550 system was utilized for WES. The study included both patients with a DRA compatible with FSHD diagnosis and patients with longer
D4Z4 alleles. In case of patients harboring relevant variants from WES, the molecular analysis was extended to the family members. Results: The WES data analysis highlighted 20 relevant variants, among which 14 were located in known genetic modifiers (SMCHD1, DNMT3B and LRIF1) and 6 in candidate genes (CTCF, DNMT1, DNMT3A, EZH2 and SUV39H1). Most of them were found together with a permissive short (4-7 RU) or borderline/long DRA (8-20 RU), supporting the possibility that different genes can contribute to disease heterogeneity in presence of a FSHD permissive background. The segregation and methylation analysis among family members, together with clinical findings, provided a more comprehensive picture of patients. Discussion: Our results support FSHD pathomechanism being complex with a multigenic contribution by several known (SMCHD1, DNMT3B, LRIF1) and possibly other candidate genes (CTCF, DNMT1, DNMT3A, EZH2, SUV39H1) to disease penetrance and expressivity. Our results further emphasize the importance of extending the analysis of molecular findings within the proband\'s family, with the purpose of providing a broader framework for understanding single cases and allowing finer genotype-phenotype correlations in FSHD-affected families.