A novel PTCH1 mutation underlies nonsyndromic cleft lip and/or palate in a Han Chinese family.

OBJECTIVES: Cleft lip and/or palate (CL/P) is the most common craniofacial congenital disease, and it has a complex aetiology. This study aimed to identify the causative gene mutation of a Han Chinese family with CL/P. SUBJECTS AND METHODS: Whole exome sequencing was conducted on the proband and her mother, who exhibited the same phenotype. A Mendelian dominant inheritance model, allele frequency, mutation regions, functional prediction and literature review were used to screen and filter the variants. The candidate was validated by Sanger sequencing. Conservation analysis and homology modelling were conducted. RESULTS: A heterozygous missense mutation c.1175C>T in the PTCH1 gene predicting p.Ala392Val was identified. This variant has not been reported and was predicted to be deleterious. Sanger sequencing verified the variant and the dominant inheritance model in the family. The missense alteration affects an amino acid that is evolutionarily conserved in the first extracellular loop of the PTCH1 protein. The local structure of the mutant protein was significantly altered according to homology modelling. CONCLUSIONS: Our findings suggest that c.1175C>T in PTCH1 (NM_000264) may be the causative mutation of this pedigree. Our results add to the evidence that PTCH1 variants play a role in the pathogenesis of orofacial clefts.

A novel FZD6 mutation revealed the cause of cleft lip and/or palate in a Chinese family.

Cleft lip and/or palate (CL/P) is a most common craniofacial birth defect which has multifactorial etiology. In our study, we aimed to discover the underlying etiological gene variation in a Chinese family diagnosed as non-syndromic CL/P (NSCL/P). The blood sample of the proband and her parents were detected by whole exome sequencing. The Mendelian inheritance pattern, allele frequency, variation location, function analysis and literature search were applied to filtrate and screen the mutation. Besides, the candidates were confirmed by Sanger sequencing. We meanwhile explored the conservative analysis and protein homology simulation. As a result, a start-lost mutation c.1A > GAtg/Gtg in the Frizzled-6 (FZD6) gene predicting p.Met1 was detected. The variation has not been reported before and was predicted to be harmful. The alteration caused missing of two starting amino acids that are evolutionarily conserved for FZD6 protein. Moreover, the specific structure of the mutant protein obviously changed according to the results of the homologous model. In conclusion, the results suggest c.1A > GAtg/Gtg in the FZD6 (NM_001164616) might be the genetic etiology for non-syndromic CL/P in this pedigree. Furthermore, this finding provided new etiologic information, supplementing the evidence that FZD6 is a strong potential gene for CL/P.

Three GLI2 mutations combined potentially underlie non-syndromic cleft lip with or without cleft palate in a Chinese pedigree.

BACKGROUND: Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is the most common craniofacial birth defect. Its etiology is complex and it has a lifelong influence on affected individuals. Despite many studies, the pathogenic gene alleles are not completely clear. Here, we recruited a Chinese NSCL/P family and explored the candidate causative variants in this pedigree. METHODS: We performed whole-exome sequencing on two patients and two unaffected subjects of this family. Variants were screened based on bioinformatics analysis to identify the potential etiological alleles. Species conservation analysis, mutation function prediction, and homology protein modeling were also performed to preliminarily evaluate the influence of the mutations. RESULTS: We identified three rare mutations that are located on a single chromatid (c.2684C > T_p.Ala895Val, c.4350G > T_p.Gln1450His, and c.4622C > A_p.Ser1541Tyr) in GLI2 as candidate causative variants. All of these three mutations were predicted to be deleterious, and they affect amino acids that are conserved in many species. The mutation c.2684C > T was predicted to affect the structure of the GLI2 protein. CONCLUSION: Our results further demonstrate that GLI2 variants play a role in the pathogenesis of NSCL/P, and the three rare missense mutations combined are probably the potential disease-causing variants in this family.