Association of single-nucleotide polymorphisms, rs2235371 and rs2013162, in the IRF6 gene with non-syndromic cleft palate in northeast China.

The aim of this study was to determine the association between two SNPs (rs2235371 and rs2013162) in the interferon regulatory factor 6 (IRF6) gene and non-syndromic cleft palate (NSCP) in northeast China. We genotyped these two SNPs in 104 NSCP cases, as well as in 178 parents and 300 controls. Case-control and case-parent analyses were performed using χ2 tests and family-based association tests (FBAT). Results indicated that there were significant differences in both genotypic and allelic distributions between patients and controls at rs2235371 and rs2013162 in the IRF6 gene. Case-parent analysis revealed over-transmission of the C allele in rs2235371 and the A allele in rs2013162. Lastly, FBAT showed over-transmission of the CA haplotype. This study demonstrated that the two SNPs, rs2235371 and rs2013162, are strongly associated with NSCP in the northeast Chinese population.

Mutation analysis of four Chinese families with pure hereditary spastic paraplegia: pseudo- X-linked dominant inheritance and male lethality due to a novel ATL1 mutation.

We studied four Chinese families with pure hereditary spastic paraplegia (HSP) to investigate the clinical features and associated genetic mutations. Linkage analysis was performed for all families to map the disease locus onto autosomal chromosomes, and related loci involved in HSP on the X chromosome were also examined. Polymerase chain reaction (PCR) sequencing was used to detect gene mutations. To confirm the influence of a splice-site mutation on mRNA, we used reverse transcription-PCR and direct sequencing. Linkage analysis and ATL1 gene sequencing of amniocytes were performed for prenatal genetic diagnosis. One missense variant (c.1517T>A) and a splice-site mutation (c.1245+1G>A) in SPAST, and two missense variants (c.715C>T, c.1204T>G) in ATL1 were identified. The c.1245+1G>A mutation caused a deletion of exon 9 in the SPAST gene. Prenatal genetic diagnosis showed that fetus did not carry the ALT1 c.1204T>G mutation. Follow-up was maintained for 5 years, and the negative result was confirmed by evidence of a healthy growing boy. We identified two novel mutations and two previously reported mutations in SPAST and ATL1, respectively. The family with the ATL1 c.1204T>G mutation exhibited male-lethality, female infancy-onset, and pseudo- X-linked dominant transmission, which had never been previously reported for HSP. Characteristic facial features were also noticed. The boy on whom prenatal gene diagnosis was performed is healthy and without unusual facies, suggesting that the c.1204T>G mutation might be related to these features. The results extend the genetic spectrum of HSP and suggest that linkage analysis remains a powerful tool in gene discovery studies.

Variations in WNT3 gene are associated with incidence of non-syndromic cleft lip with or without cleft palate in a northeast Chinese population.

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect. Several WNT genes are involved in craniofacial embryogenesis, and therefore may play an important role in the etiology of NSCL/P. Two SNPs (rs3809857 and rs9890413) in the WNT3 gene were subjected to case-control and case-parent analysis by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 236 unrelated patients with NSCL/P, including 128 elementary families (185 mothers and 154 fathers), and 400 control individuals from northeast China. The rs3809857 SNP, under the assumption of a dominant model, was found to induce a 2-fold lower risk of NSCL/P ORGG vs GT + TT = 0.605, 95%CI = 0.436-0.839, P = 0.003). Moreover, the family-based association test revealed an under-transmission for the minor allele T. On the other hand, we observed a significant association in the case-control and case-parent analysis of the SNP rs9890413. In addition, the P values for the haplotype of rs3809857-rs9890413 were observed to be statistically significant (P = 0.004). In conclusion, our study confirmed the association between the WNT3 variant and NSCL/P in the population tested.

A novel mutation of the MFN2 gene in a Chinese family with Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth (CMT) is a group of clinically and genetically heterogeneous inherited neuromuscular disorders. At present, more than 30 loci have been reported to be associated with CMT disease; point mutations in the mitofusin 2 (MFN2) gene is one of the most common causes. We studied a Chinese family with CMT disease in which the phenotype of affected individuals varied, and the weakness condition of the distal legs in males, except the proband, was less severe than in females in this family. Linkage analysis and PCR sequencing revealed a missense mutation (NM_014874.3:c.1066 A>G) in the MFN2 gene, resulting in an animo acid substitution of threonine to alanine in condon 356 (Thr356Ala). This is a novel phenotype and mutation for CMT family.