[Mutations in the ED1 gene in families with X-linked hypohidrotic ectodermal dysplasia].

OBJECTIVE: To detect mutations in the ED1 gene in two Chinese pedigrees and a sporadic case with X-linked hypohidrotic ectodermal dysplasia (XLHED) and provide evidences with the mutation analysis for genetic counseling, prenatal diagnosis and confirmation of carrier status. METHODS: Peripheral blood samples were obtained from two pedigrees and the sporadic patient, and genomic DNA was extract by salting out method. Polymerase chain reaction (PCR) and direct sequencing were performed to screen mutations in ED1 gene. RESULTS: Three mutations were identified. In one of the pedigrees, a 1045G > A transition was evidenced in exon 9 that resulted in a change of Ala 349 Thr. In the other pedigrees and the sporadic patient, 467G > A and 466C > T transitions were demonstrated in exon 3 that resulted in change of Arg 156 His and Arg 156 Cys. These mutations were not found in 100 normal individuals. CONCLUSIONS: These mutations were responsible for the disease in the two families and the sporadic patient. All these mutations had been identified previously.

Identification of novel mutations of IRF6 gene in Chinese families with Van der Woude syndrome.

Van der Woude syndrome (VWS) is an autosomal dominant disorder of syndromic clefts clinically characterized by lower lip pits, cleft lip and/or palate, hypodontia. Mutations in the IRF6 gene have recently been found to cause VWS and more than 70 mutations have been reported. However, genotype distribution and prevalence of IRF6 mutations underlying Chinese are largely unknown. In the present study, we report on four Chinese families with VWS. Considerably variable clinical phenotypes were observed between and within each family. By direct sequencing, three novel mutations (Y111H, S407fsX436, F165fsX166) as well as a recurrent mutation (R400W) were identified. In contrast to the IRF6 mutations reported in Caucasians, the majority of these mutations occurred at a run of 1- or 2-base repetitive sequence unit, and localized neither in the conserved DNA-binding domain nor in the Smad-interferon regulatory factor-binding domain (SMIR). Therefore, our results indicate the existence of other putative IRF6 regions that are predisposed to mutations. Repeated nucleotides in the IRF6 coding regions may increase the instability and chance of DNA replication errors, and are prone to be potential mutation hot-spots.

[The study of salivary-SIgA reaction to Streptococcus mutans in acid environment].

OBJECTIVE: To test the salivary immunoglobulin A antibody activity to Streptococcus mutans in normal with in acid environment. METHODS: Streptococcus mutans strains were isolated from 20 volunteers, serotyped by biochemical test and PCR, and genotyped by AP-PCR. Unstimulated secretions from submandibular glands and sublingual glands were collected from volunteers by modified collectors. Each identified Streptococcus mutans genotype was cultured in two groups: control group was cultured in BHI broth pH7.2 at 37 degrees C for 2 h; acid shock group were cultured in TYEG broth (pH5.5) at 37 degrees C for 2 h. Analysis of SIgA activity to Streptococcus mutans genotypes in different groups was detected by Western blot. RESULTS: (1) The SIgA of each individual could response to his own Streptococcus mutans strains and the reference strains; (2) The same individual had different SIgA activity to different genotype strains; (3) There were no significant difference between acid groups and control groups, in spite that some bands had strong or weak intensity. CONCLUSIONS: Although Streptococcus mutans could express acid shock proteins in stress, the present study suggests that these new proteins have no qualitative effect on the reaction of SIgA to Streptococcus mutans.