Pratical techniques of mutation detections for particular genetic diseases in Thai patients

Abstract

Genetic disorders are caused by mutations in genes or abnormalities of chromosomes. The abnormality can range from a discrete mutation in a single base in the DNA to a gross chromosome abnormality. There are several methods for mutation detection. In this study, we demonstrated some of methods to properly characterize genetic diseases that were identified at Pediatric Clinic of the King Chulalongkorn Memorial Hospital. We have collected 9 patients with X-Adrenoleukodystrophy (X-ALD) and performed PCR-sequencing of entire coding region of the ABCD1 gene. Three known mutations, A646P, E609K, R401W and two novel mutations, L392P and A247D were detected. We also analyzed the GAA gene causing Pompe disease by PCR-RFLP or direct sequencing on the previously reported mutations in the Chinese population. The possible founder effect mutation, D645E was found in all families and G576S known mutation in one family. A recently identified gene responsible for hyper-IgE syndrome (HIE) was also studied in one patient. Direct sequencing covering the region coding for the DNA binding and SH2 domains in the STAT3 gene was performed and revealed the known mutation, R382W on the DNA binding domain. We also found 4 patients with clinical features consistent with Holt-Oram syndrome. However, PCR-direct sequencing could not identify disease-causing mutations in the TBX5 and SALL4 genes. Finally, a possible candidate gene, DcR3, for SLE was characterized. ELISA was used to detect the level of DcR3 in serum of 52 SLE patients and 25 controls who were unaffected with SLE. The DcR3 levels were significantly higher in the active group compared to the inactive SLE patients. However, there was no difference between the SLE patients and the unaffected controls. Interesting, a novel mutation, H122Y, was detected in the DcR3 gene in one SLE patient. The mutation was on the Fas binding domain. Further studies are required to elucidate its functional significance.