A novel termination codon mutation of the WAS gene in a Thai family with Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by microthrombocytopenia, eczema, immunodeficiency, and susceptibility to lymphoid malignancy. Loss-of-function mutations in WAS gene have been identified to cause disorders with platelet defects including WAS and X-linked thrombocytopenia. Mutations anticipated to yield truncated or no protein have been associated with the more severe presentations of WAS. Activating mutations in WAS gene result in an entirely different phenotype, an X-linked severe congenital neutropenia. We describe a Thai family with classic WAS. The proband, a one-year-old boy presented with recurrent mucous bloody diarrhea, recurrent otitis media, chronic eczema, thrombocytopenia, and small platelet sizes. The patient's older brother who also had persistent thrombocytopenia died at the age of seven months from severe pneumonia. Immunoblot analysis demonstrated that the proband's cells lacked WAS protein expression. Mutation analysis of the proband and his mother for the entire coding region of WAS identified a novel type of mutation, a termination codon mutation, X503R. The change is expected to result in an elongated mRNA that would code for a WASP of 581 amino acid residues instead of the normal 502 residues. Because of the absence of WASP expression, we speculate that the termination codon mutation causes reduced mRNA stability. Our findings supported that WAS mutations resulted in no protein are associated with a severe phenotype of WAS.     

A novel mutation, 1234del(C), of the IRF6 in a Thai family with Van der Woude syndrome

Van der Woude syndrome (VWS) is an autosomal dominant disorder and the most common cleft syndrome characterized by cleft lip and palate with lip pits. Very recently, mutations in the interferon regulatory factor 6 gene (IRF6) were identified to cause VWS in patients of northern European descent. We describe a Thai family with VWS. The proband, an 8-month-old boy, had bilateral complete cleft lip and palate, and two conical elevations with lip pits on his lower lip. Four other family members had various manifestations of the clefts and lower lip pits. Mutation analysis of the proband and his mother for the entire coding region of IRF6 identified a novel mutation, 1234del(C), in its exon 9. The deletion is expected to result in some amino acid changes followed by truncation at amino acid 435. This observation supports that IRF6 is the gene responsible for VWS across different populations and that haploinsufficiency of the gene disturbs development of the lip and palate.     

PDGFRa mutations in humans with isolated cleft palate

Isolated cleft palate (CP) is common in humans and has complex genetic etiologies. Many genes have been found to contribute to CP, but the full spectrum of genes remains unknown. PCR-sequencing of the entire coding regions and the 3′ untranslated region (UTR) of the platelet-derived growth factor receptor alpha (PDGFRa) and the microRNA (miR), miR-140 identified seven novel single base-pair substitutions in the PDGFRa in 9/102 patients with CP (8.8%), compared with 5/500 ethnic-matched unaffected controls (1%) (the two-tailed P-value<0.0001). Of these seven, four were missense mutations in the coding regions and three in the 3′UTR. Frequencies of four changes (three in coding, one in 3′UTR) were statistically different from those of controls (P-value<0.05). The c.*34G>A was identified in 1/102 cases and 0/500 controls. This position is conserved in primates and located 10 bp away from a predicted binding site for the miR-140. Luciferase assay revealed that, in the presence of miR-140, the c.*34G>A significantly repressed luciferase activity compared with that of the wild type, suggesting functional significance of this variant. This is the first study providing evidence supporting a role of PDGFRa in human CP.     

Significant association between IRF6 820G→A and non-syndromic cleft lip with or without cleft palate in the Thai population

Background: Previous data have shown an association between DNA sequence variants in the IRF6 gene and an increased risk of non-syndromic cleft lip with or without cleft palate (CL/P) in some populations.

Objective: To investigate Thai CL/P patients and relative for a 820G→A polymorphism.

Subjects: 192 CL/P Thai patients, 177 of their mothers, 73 of their fathers, and 278 controls.

Results: There were significant differences in the frequency distributions of both genotypes (p = 0.02) and alleles (p = 0.04) among probands as compared with the control group. The odds ratio calculated for the patients having the GG genotype compared with the other two genotypes (GA and AA) was 1.67 (95% confidence interval, 1.13 to 2.47). This pattern is consistent with a recessive effect of the G allele. No association between any of the parents' genotypes and CL/P was found. The IRF6 820G→A was responsible for 16.7% of the genetic contribution to CL/P.

Conclusions: The findings confirm that IRF6 820G→A is associated with CL/P.

     

Ring B aromatic norpimarane glucoside from a Xylaria sp

A novel 20-norpimarane glucoside, xylopimarane (1), together with the known sphaeropsidin C (2) and clonostachydiol (3), was isolated from the fungus Xylaria sp. BCC 4297. Compound 1 exhibited cytotoxicity to cancer cell lines KB, MCF-7, and NCI-H187 with respective IC(50) values of 1.0, 13, and 65 μM.