Whole genome sequencing for the identification and verification of causative genes involved in orbital hypertelorism patients—3 monozygotic twins
10.3760/cma.j.cn114453-20200701-00395
- VernacularTitle:全基因组测序鉴定3对单卵双胞胎中眶距增宽症致病基因突变及其验证研究
- Author:
Liqin LIN
1
;
Shanshan BAI
;
Zheyuan YU
;
Liang XU
;
Huichuan DUAN
;
Yijia ZHU
;
Min WEI
;
Jie YUAN
Author Information
1. 上海交通大学医学院附属第九人民医院整复外科 200011
- Keywords:
Twins, monozygotic;
Orbital hypertelorism;
MAML3
- From:
Chinese Journal of Plastic Surgery
2021;37(9):1049-1056
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To identify the gene mutations associated with facial cleft-related orbital hypertelorism in 3 pairs of monozygotic twins with different phenotypes (with/without hypertelorism) and to investigate their mechanisms.Methods:From May 2014 to May 2019, 3 pairs of monozygotic twins, 2 males and 4 females, aged 5-18 years, were treated in Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, one with normal orbital distance and widening of orbital distance was caused by facial fissure. Among the twins, there was 1 case of orbital hypertelorism and the other case of without orbital hypertelorism, and the hypertelorism was caused by facial cleft. To screen for mutations in hypertelorism, whole genome sequencing was performed on 3 pairs of twins. The Sanger method was used to sequence the exons of 33 patients with facial fissure associated hypertelorism and 50 healthy individuals in the same period to identify the genes selected by the whole genome sequencing. The periosteal tissues were obtained from patients and healthy people during plastic surgery. The cells were cultured, the activity of alkaline phosphatase was measured, and the osteogenic differentiation was identified by alizarin red staining, real-time quantitative PCR and Western blotting were used to detect the mRNA and protein expression of signal transduction pathways in periosteal cells.Results:Whole genome sequencing analysis showed that in all three sets of twins, a new synonymous mutation (c.1479G>A, p. Q493Q) was found in the MAML3. In Sanger exon sequencing, 17(51.5%) of 33 patients with hypertelorism carried the mutation, while no mutation was detected in 50 normal controls. The result of periosteum-derived cytology showed that the expression of MAML3 mRNA and protein in the patient-derived cells was lower than that in the healthy-derived cells. Three, 7, 14 days after osteoinduction, the ALP activity in the cells from the patients was higher than that from the healthy subjects (8.540±1.450, 20.740±2.514, 24.090±3.213 vs. 5.268±0.482, 11.680±1.527, 13.200±0.592; all P<0.05). Fourteen days after osteoinduction, the result of alizarin red staining showed that there were more erythema formation in the cells from the patients than those from the healthy subjects, these result suggest that MAML3 mutation may lead to over-differentiation of human periosteal-derived cells. The mRNA and protein expression levels of hes1 and hes5 downstream of the Notch signal pathway were down-regulated in the periosteal cells of the patients, while Wnt3a and β-catenin mRNA and protein expression levels were up-regulated in the Wnt signal pathway. Conclusions:The MAML3 gene (c.1479G>A, p. Q493Q) mutation is one of the causative genes of facial cleft-related hypertelorism. Notch and Wnt/β-catenin signaling pathway play an important role in the pathogenesis of hypertelorism.
