Yann-Jinn Lee

Identification of Novel Susceptibility Loci for Kawasaki Disease in a Han Chinese Population by a Genome-Wide Association Study

Kawasaki disease (KD) is an acute systemic vasculitis syndrome that primarily affects infants and young children. Its etiology is unknown; however, epidemiological findings suggest that genetic predisposition underlies disease susceptibility. Taiwan has the third-highest incidence of KD in the world, after Japan and Korea. To investigate novel mechanisms that might predispose individuals to KD, we conducted a genome-wide association study (GWAS) in 250 KD patients and 446 controls in a Han Chinese population residing in Taiwan, and further validated our findings in an independent Han Chinese cohort of 208 cases and 366 controls. The most strongly associated single-nucleotide polymorphisms (SNPs) detected in the joint analysis corresponded to three novel loci. Among these KD-associated SNPs three were close to the COPB2 (coatomer protein complex beta-2 subunit) gene: rs1873668 (p = 9.52×10−5), rs4243399 (p = 9.93×10−5), and rs16849083 (p = 9.93×10−5). We also identified a SNP in the intronic region of the ERAP1 (endoplasmic reticulum amino peptidase 1) gene (rs149481, pbest = 4.61×10−5). Six SNPs (rs17113284, rs8005468, rs10129255, rs2007467, rs10150241, and rs12590667) clustered in an area containing immunoglobulin heavy chain variable regions genes, with pbest-values between 2.08×10−5 and 8.93×10−6, were also identified. This is the first KD GWAS performed in a Han Chinese population. The novel KD candidates we identified have been implicated in T cell receptor signaling, regulation of proinflammatory cytokines, as well as antibody-mediated immune responses. These findings may lead to a better understanding of the underlying molecular pathogenesis of KD.

Solitary maxillary central incisor and congenital nasal pyriform aperture stenosis

Abstract Solitary maxillary central incisor (SMCI) and congenital nasal pyriform aperture stenosis (CNPAS) have been reported as an isolated morphogenic defect or associated with pituitary deficiency, holoprosencephaly, ocular coloboma, or chromosomal abnormalities. We report two cases and analyse 40 cases of SMCI and 24 cases of CNPAS, including 15 cases of combined SMCI and CNPAS, obtained from the literature. Of the patients with SMCI, 69% had short stature, 48% growth hormone deficiency or hypopituitarism, 23% pituitary absence or hypoplasia, and 17% had del (18p-) or r(18). Of the patients with CNPAS, 63% had SMCI, 75% were short, 43% had hypopituitarism or growth hormone deficiency, 36% had pituitary or CNS anomaly, and 33% had del (18p), r(18), or del (13q). Conclusions Solitary maxillary central incisor and congenital nasal pyriform aperture stenosis can be a diagnostic clue to pituitary hypofunction, CNS, ophthalmological and cytogenic anomalies.

Identification of four novel mutations in the CYP21 gene in congenital adrenal hyperplasia in the Chinese

Abstract Congenital adrenal hyperplasia (CAH) is a common autosomal recessive disorder mainly caused by defects in the steroid 21-hydroxylase (CYP21) gene. We have analyzed CYP21 gene sequences in 65 CAH families in Taiwan. All ten exons of the CYP21 gene were analyzed by differential polymerase chain reaction followed by single-strand conformation polymorphism electrophoresis and the amplification-created restriction site method. About 95% (123 chromosomes) contain mutations due to conversion of DNA sequences into its neighboring homologous pseudogene, CYP21P. Four novel mutations representing 5% of the total chromosomes have also been identified. The mutations were confirmed by sequencing an aberrant DNA fragment. These four mutations included a base change of the splicing donor site at intron 2 from GT to AT, a base substitution of C to T at codon 316, deletion of ten bases (TCCAGCTCCC) at codons 330–333 of exon 8, and duplication of 16 bases (CCTGGATGACACGGTC) at codons 393–397 of exon 9. The loss of the splicing donor site at intron 2 and the premature stop at codon 316 may result in aberrant splicing to reduce enzyme activity and a truncated protein with no enzyme activity, respectively. Likewise, both the duplication and the deletion forms create a frameshift and premature stop during translation. The resulting proteins lack the heme-binding domain and hence are expected to lose enzymatic activity. Since these mutations are not found in the neighboring CYP21P pseudogene, gene conversion should not be the cause of these novel mutations.

Association of CTLA4 gene A-G polymorphism with rheumatoid arthritis in Chinese.

The aim of this study was to investigate the allelic association of a single nucleotide polymorphism in exon 1 of the cytotoxic T-lymphocyte antigen-4 (CTLA4) gene with rheumatoid arthritis (RA) in Chinese people. One hundred and eighty-six unrelated adults with RA and 203 randomly selected normal adults were studied. All were ethnic Chinese living in Taiwan. The CTLA4 A-G polymorphism was genotyped with a polymerase chain reaction (PCR) and digestion with the restriction enzyme BstEII. The genotype and allele frequencies of CTLA4 in patients with rheumatoid arthritis differed significantly from those of adult controls (#E5/E5#=0.022 and #E5/E5#=0.037, respectively). Genotype CTLA4 49 G/G and allele G were associated with an increased risk of RA (RR=1.72, 95% CI=1.15–2.57, #E5/E5#=0.008; RR=1.39, 95% CI=1.02–1.89, #E5/E5#=0.037, respectively), whereas genotype A/G and allele A were associated with protection against RA (RR=0.58, 95% CI=0.39–0.87, #E5/E5#=0.008 and RR=0.72, 95% CI=0.53–0.98, #E5/E5#=0.037, respectively). We concluded that, the CTLA4 49 A-G polymorphism is associated with RA in Chinese patients from Taiwan.

Association of CTLA4 gene A–G polymorphism with type 1 diabetes in Chinese children†

The CTLA4 (cytotoxic T lymphocyte associated antigen‐4) gene encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis. Thus it is a strong candidate gene for T cell‐mediated autoimmune disease. There is polymorphism at position 49 in exon 1 of the CTLA4 gene, providing a A–G exchange. This polymorphism is reportedly associated with type 1 diabetes in Caucasians but not in a small data set of Chinese. We wished to test this polymorphism in a larger and more homogeneous data set of Chinese children with type 1 diabetes and normal adult controls.

Polymorphism of Transmembrane Region of MICA Gene and Kawasaki Disease

Kawasaki disease is a febrile disease of children complicated with vasculitis of the coronary arteries and potential aneurysm formation. It has been recognized worldwide and appears to be increasing in frequency. Studies have found that Kawasaki disease is associated with major histocompatibility complex (MHC) class I B antigens. The MHC-class-I-chain-related gene A (MICA) is located near HLA-B. It has a triplet repeat microsatellite polymorphism in the transmembrane region. We investigated the microsatellite polymorphism in children with Kawasaki disease and controls. Seventy children (46 boys), age at diagnosis 1.68 ± 1.69 years, with Kawasaki who were treated with aspirin as well as intravenous gamma-globulin were enrolled. Control subjects consisted of 154 children (87 boys), age 2.81 ± 2.12 years. Phenotype frequency of allele A4 in patients with aneurysm formation was significantly lower than in patients without aneurysms [relative risk (RR) = 0.06, 95% confidence interval (CI) = 0.01–0.48, p = 0.00469, pc = 0.0232] and showed a similar tendency when compared with controls. Gene frequency of allele A4 was also significantly lower in patients who developed aneurysms than in patients who did not (RR = 0.07, 95% CI = 0.01–0.57, p = 0.0057, pc = 0.0282). Gene frequency of allele A5 showed a tendency to be higher in patients who developed aneurysms than in controls (RR = 2.35, 95% CI = 0.98–5.63, p = 0.0486, pc = 0.220). Allele A5.1 tended to be negatively associated with Kawasaki disease (RR = 0.57, 95% CI = 0.35–0.93, p = 0.022, pc = 0.105). Our study showed that allele A4 was negatively associated with coronary aneurysm formation in Kawasaki disease. This suggests that allele A4 protects the children with Kawasaki disease from developing coronary aneurysms after aspirin and gamma globulin therapy.

Genetic Variation in the Vascular Endothelial Growth Factor Gene is Associated With Biliary Atresia

Background and Goals: Biliary atresia (BA) is a chronic inflammatory disease of the bile ducts resulting in biliary cirrhosis. Vascular endothelial growth factor (VEGF) has been implicated in cell-mediated inflammatory reactions. We aimed to study the relationship between genetic variations of the VEGF gene and susceptibility to BA using both case-control and family-based methodologies. Study: A total of 45 Taiwanese children with BA, 160 ethnically matched healthy controls, and 40 families (consisting of parents, affected children, and unaffected siblings) were studied. Three functional VEGF polymorphisms (−2578 A/C, −634 G/C, and +936 C/T) were assessed by using TaqMan assay. Results: The +936 CC genotype [odds ratio (OR) 3.51, 95% confidence interval 1.54-8.01, Pc=0.006] and C allele (OR 3.19, 95% confidence interval 1.48-6.90, Pc=0.004) were significantly associated with increased risk of BA. The association of the +936 C allele with BA was also confirmed in a family-based association study (OR 5.7, χ2=9.8, Pc=0.005). None of the haplotypes studied significantly influenced the risk to BA in either the case-control or family data sets. Conclusions: The VEGF +936 C/T polymorphism and particularly the C allele are associated with BA, possibly conferring increased susceptibility to the disease.

ITPKC gene SNP rs28493229 and Kawasaki disease in Taiwanese children

Kawasaki disease (KD) is a systemic vasculitis caused by unknown infectious agents, host immune dysregulation and genetic susceptibility in children. Coronary artery lesions (CALs) complicate 15-25% of cases of untreated KD. The aim of this study was to investigate if the single-nucleotide polymorphism (SNP) rs28493229 of the ITPKC gene is associated with susceptibility to KD or with CALs in Taiwanese children. A total of 385 unrelated Taiwanese children (222 boys and 163 girls) with KD were included, 140 of whom had CALs. Mean age at diagnosis was 1.9 +/- 1.7 (0.1-10.2) years. Rs28493229 was genotyped in children with KD and 1158 ethnically matched healthy controls using the TaqMan Allelic Discrimination Assay. In 184 families with KD, both biological parents were available, constituting 184 trios with their children. They were assessed in a family-based study by means of a transmission/disequilibrium test (TDT). No significant differences in genotype (P = 0.29 and P = 0.29, respectively), allele (P = 0.14 and P = 0.22, respectively) and carrier (P = 0.22 and P = 0.25, respectively) frequencies of the SNP were found between healthy controls and children with KD or those with CALs. TDT in the 184 family trios and in 69 trios where the child had CALs did not reveal significant overtransmittion of the C allele. In conclusion, we did not find a statistically significant association between the ITPKC gene SNP rs28493229 and KD or CALs in Taiwanese children.

Polymorphism in the transmembrane region of the MICA gene and type 1 diabetes.

Although MHC class II genes have a stronger association with type 1 diabetes than MHC class I genes, studies have shown that MHC class I molecules play an independent role in the etiology of type 1 diabetes, and the existence of susceptibility genes within a segment of MHC between the HLA-B and TNF genes has been predicted, where MHC class I chain-related gene A (MICA) resides. MICA has a triplet repeat polymorphism in the transmembrane region consisting of five alleles. We analyzed this polymorphism in 162 unrelated children (82 boys) with type 1 diabetes (age at diagnosis 7.01 +/- 3.76 yr) and 154 randomly selected unrelated children (87 boys), age 2.81 +/- 2.12 yr. Phenotype frequency of allele A9 in children with type 1 diabetes was significantly higher than in controls (RR = 2.42, 95% CI = 1.52-3.85, p = 0.000162, pc = 0.00081). Gene frequency of allele A9 was also significantly higher in children with type 1 diabetes when compared with control children (RR = 2.73, 95% CI = 1.85-4.03, p = 2.62 x 10(-7), pc = 1.31 x 10(-6)). This study demonstrates that MICA allele A9 confers risk of type 1 diabetes.

Impact of physical activity on heart rate variability in children with type 1 diabetes

ObjectiveChildren with type 1 diabetes are usually associated with cardiovascular autonomic neuropathy. The present study explored the influence of physical activity on their autonomic nervous function by measuring the heart rate variability (HRV).Materials and methodsA total of 93 type 1 diabetic children and 107 healthy control subjects were enrolled. The Physical Activity Questionnaire for Children (PAQ-C) was adopted to determine the physical activity level as low, moderate, or high activity. HRV was determined by frequency analysis and measured in both resting and active states.ResultsChildren with type 1 diabetes had significantly lower HRV than that of healthy control subjects in resting state but not in active state. The decreased HRV in diabetic children was observed only in subjects with low physical activity. The HRV in diabetic children with moderate to high physical activity, however, was not different from that of their healthy controls.ConclusionsDiabetic children should be encouraged to engage in physical activity with more intensity, which can benefit their autonomic nervous function. Nevertheless, the potential risk of vigorous activity still needs our concern.