Kouji Higashi

A genome-wide association study identifies three new risk loci for Kawasaki disease

We performed a genome-wide association study (GWAS) of Kawasaki disease in Japanese subjects using data from 428 individuals with Kawasaki disease (cases) and 3,379 controls genotyped at 473,803 SNPs. We validated the association results in two independent replication panels totaling 754 cases and 947 controls. We observed significant associations in the FAM167A-BLK region at 8p22-23 (rs2254546, P = 8.2 × 10−21), in the human leukocyte antigen (HLA) region at 6p21.3 (rs2857151, P = 4.6 × 10−11) and in the CD40 region at 20q13 (rs4813003, P = 4.8 × 10−8). We also replicated the association of a functional SNP of FCGR2A (rs1801274, P = 1.6 × 10−6) identified in a recently reported GWAS of Kawasaki disease. Our findings provide new insights into the pathogenesis and pathophysiology of Kawasaki disease.

Prognostic Impact of Vascular Leakage in Acute Kawasaki Disease

Background Increased microvascular permeability is an initial step of Kawasaki disease (KD). We reported that vascular endothelial growth factor (VEGF) might play a role in the vascular leakage of KD. In fatal KD, plasma leakage was extensively documented at VEGF‐positive microvessels. Increases in vascular leakage cause hypoalbuminemia and noncardiogenic edema. However, the prognostic impact of vascular leakage in KD remains unclear. Methods and Results We compared 76 patients who became afebrile within 5 days after starting intravenous gamma globulin (IVGG) (2 g/kg over 5 days) (IVGG‐responsive) with 27 patients who did not respond (IVGG‐resistant). Baseline levels of serum VEGF and albumin were similar between the groups. After IVGG, VEGF levels increased (P<0.0001) and albumin levels decreased (P<0.00001) in both groups. However, the IVGG‐resistant group had higher VEGF levels (P=0.029) and severe hypoalbuminemia (P<0.00001) compared with the IVGG‐responsive group. Coronary aneurysms were documented in 12 patients from the IVGG‐resistant group but not in the IVGG‐responsive group. Then IVGG‐resistant patients were divided into 2 subgroups according to the presence (n=12) or absence (n=15) of coronary aneurysms. There was no difference between subgroups in age, sex, laboratory data including albumin, and retreated doses of IVGG. However, body weight gain after IVGG was documented in patients who subsequently developed coronary aneurysms (P=0.003) but not in those who did not (P=0.967). Conclusions These results suggest that vascular leakage may be a key feature of KD pathophysiology. The present study may provide better insights into the pathogenesis and treatment of patients resistant to IVGG in acute KD. (Circulation. 2003;108:325‐330.)

ITPKC and CASP3 polymorphisms and risks for IVIG unresponsiveness and coronary artery lesion formation in Kawasaki disease

Functional single-nucleotide polymorphisms (SNPs) in inositol 1,4,5-trisphosphate 3-kinase C (ITPKC) (rs28493229) and caspase-3 (CASP3) (rs113420705; formerly rs72689236) are associated with susceptibility to Kawasakis disease (KD). To evaluate the involvement of these 2 SNPs in the risk for intravenous immunoglobulin (IVIG) unresponsiveness, we investigated 204 Japanese KD patients who received a single IVIG dose of 2 g kg−1 (n=70) or 1 g kg−1 daily for 2 days (n=134). The susceptibility allele of both SNPs showed a trend of overrepresentation in IVIG non-responders and, in combined analysis of these SNPs, patients with at least 1 susceptible allele at both loci had a higher risk for IVIG unresponsiveness (P=0.0014). In 335 prospectively collected KD patients who were treated with IVIG (2 g kg−1), this 2-locus model showed a more significant association with resistance to initial and additional IVIG (P=0.011) compared with individual SNPs. We observed a significant association when all KD patients with coronary artery lesions were analyzed with the 2-locus model (P=0.0031). Our findings strongly suggest the existence of genetic factors affecting patients’ responses to treatment and the risk for cardiac complications, and provide clues toward understanding the pathophysiology of KD inflammation.

Zebrafish Gene Knockdowns Imply Roles for Human YWHAG in Infantile Spasms and Cardiomegaly

Williams‐Beuren syndrome (WBS) is a neurodevelopmental disorder presenting with an elfin‐like face, supravalvular aortic stenosis, a specific cognitive‐behavioral profile, and infantile hypercalcemia. We encountered two WBS patients presenting with infantile spasms, which is extremely rare in WBS. Array comparative genomic hybridization (aCGH) and fluorescent in situ hybridization (FISH) analyses revealed atypical 5.7‐Mb and 4.1‐Mb deletions at 7q11.23 in the two patients, including the WBS critical region and expanding into the proximal side and the telomeric side, respectively. On the proximal side, AUTS2 and CALN1 may contribute to the phenotype. On the telomeric side, there are two candidate genes HIP1 and YWHAG. Because detailed information of them was unavailable, we investigated their functions using gene knockdowns of zebrafish. When zebrafish ywhag1 was knocked down, reduced brain size and increased diameter of the heart tube were observed, indicating that the infantile spasms and cardiomegaly seen in the patient with the telomeric deletion may be derived from haploinsufficiency of YWHAG. genesis 48:233–243, 2010.

Variations in ORAI1 Gene Associated with Kawasaki Disease

Kawasaki disease (KD; MIM#61175) is a systemic vasculitis syndrome with unknown etiology which predominantly affects infants and children. Recent findings of susceptibility genes for KD suggest possible involvement of the Ca(2+)/NFAT pathway in the pathogenesis of KD. ORAI1 is a Ca(2+) release activated Ca(2+) (CRAC) channel mediating store-operated Ca(2+) entry (SOCE) on the plasma membrane. The gene for ORAI1 is located in chromosome 12q24 where a positive linkage signal was observed in our previous affected sib-pair study of KD. A common non-synonymous single nucleotide polymorphism located within exon 2 of ORAI1 (rs3741596) was significantly associated with KD (P = 0.028 in the discovery sample set (729 KD cases and 1,315 controls), P = 0.0056 in the replication sample set (1,813 KD cases vs. 1,097 controls) and P = 0.00041 in a meta-analysis by the Mantel-Haenszel method). Interestingly, frequency of the risk allele of rs3741596 is more than 20 times higher in Japanese compared to Europeans. We also found a rare 6 base-pair in-frame insertion variant associated with KD (rs141919534; 2,544 KD cases vs. 2,414 controls, P = 0.012). These data indicate that ORAI1 gene variations are associated with KD and may suggest the potential importance of the Ca(2+)/NFAT pathway in the pathogenesis of this disorder.

Efficacy and safety of tolvaptan for pediatric patients with congestive heart failure. Multicenter survey in the working group of the Japanese Society of PEdiatric Circulation and Hemodynamics (J-SPECH).

BACKGROUND Tolvaptan, a vasopressin V2-receptor antagonist, has been reported to improve congestion in adult patients with heart failure. However, it has not been fully clarified whether tolvaptan is also effective and safe for pediatric patients as well as adult. METHODS This trial was a multicenter, retrospective, observational study, and was led by the Japanese Society of PEdiatric Circulation and Hemodynamics (J-SPECH). Thirty-four pediatric patients who received tolvaptan to treat congestive heart failure were enrolled in this study. RESULTS An increment in the urinary volume and decrease in the body weight from baseline were significant at day 1 (+106.7 ± 241.5%, p = 0.008 and -2.30 ± 4.17%, p = 0.01), day 3 (+113.5 ± 261.9%, p = 0.02 and -2.30 ± 4.17%, p = 0.01), week 1 (+56.3 ± 163.5%, p = 0.01 and -1.55 ± 4.09%, p = 0.03) and month 1 (+91.1 ± 171.6%, p = 0.01 and -2.95 ± 5.98, p = 0.03). The significant predictive factors in responders, who was defined as patients who achieved an increase in the urinary volume at day 1, were older age (p = 0.03), larger body weight before exacerbation (p = 0.04), higher weight at one day before the first administration of tolvaptan (p = 0.03), higher aspartate aminotransferase levels (p = 0.03) and higher urinary osmolality levels (p = 0.03). A logistic regression analysis showed that the urinary osmolality was the only significant predictive factor for responders to tolvaptan. Adverse drug reactions were observed in 7 patients (20.6%). Six patients had thirst and a dry month, and 1 had a mild increase in the alanine aminotransferase and aspartate aminotransferase. CONCLUSION Tolvaptan can be effectively and safely administered in pediatric patients. Because the kidneys in neonates and infants are resistant to arginine vasopressin, the efficacy of tolvaptan may be less effective compared to older children.

Sheath placement in femoral artery during cardiac catheterization in children can influence pressure waveform

INTRODUCTION It is reported that pressure wave reflection is enhanced by external compression of the femoral artery. Therefore, it is possible that cardiac catheterization itself can influence the aortic pressure waveform. AIM The purpose of this study is to clarify the influence of sheath placement in a femoral artery on the pressure waveform. METHODS This study enrolled 21 pediatric patients (5.1±4.0years) who underwent cardiac catheterization. A sheath was placed in the femoral arteries of all patients. The change in the pressure waveform induced by the placement of the sheath was investigated using the b/a and d/a ratio of second derivative of a fingertip photoplethysmogram. A high b/a ratio means a stiff aorta and a low d/a ratio represents an enhancement of the aortic pressure wave reflection. RESULTS By the placement of the sheath in their femoral arteries, the b/a ratio was not influenced (sheath (-): -0.556±0.081 vs. sheath (+): -0.558±0.072; p=0.896). However, the d/a ratio was significantly decreased (-0.150±0.074 vs. -0.185±0.084; p=0.0003). CONCLUSIONS The placement of the femoral arterial sheath enhances the pressure wave reflection and would lead to a change in the central aortic pressure waveform.

Successful Selective Intra‐arterial Thrombolytic Therapy for Embolic Stroke in a Patient with Asplenia Syndrome and Unrepaired Cyanotic Congenital Heart Disease

We report successful selective local intra-arterial thrombolytic therapy for thromboembolic occlusion of right middle cerebral artery in a patient with asplenia syndrome and unrepaired cyanotic congenital heart disease.