Molecular and clinical features of KATP -channel neonatal diabetes mellitus in Japan.

BACKGROUND: There are few reports pertaining to Asian patients with neonatal diabetes mellitus (NDM) caused by activating mutations in the ATP-sensitive potassium channel genes (KATP-NDM). OBJECTIVES: To elucidate the characteristics of Japanese patients with KATP-NDM. METHODS: By the amplification and direct sequencing of all exons and exon-intron boundaries of the KCNJ11 and ABCC8 genes, 25 patients with KATP-NDM were identified from a total of 70 patients with NDM. Clinical data were collected from the medical charts. RESULTS: Sixteen patients had mutations in KCNJ11 and nine in ABCC8. Eight novel mutations were identified; two in KCNJ11 (V64M, R201G) and six in ABCC8 (R216C, G832C, F1176L, A1263V, I196N, T229N). Interestingly, V64M caused DEND (developmental delay, epilepsy, neonatal diabetes) syndrome in our patient, while mutation of the same residue (V64G) had been reported to cause congenital hyperinsulinism. Mutations in ABCC8 were associated with TNDM (4/9) or isolated PNDM (5/9), whereas those in KCNJ11 were associated with more severe phenotypes, including DEND (3/16), iDEND (intermediate DEND, 4/16), or isolated PNDM (6/16). Switching from insulin to glibenclamide monotherapy was successful in 87.5% of the patients. Neurological improvement was observed in two patients, one with DEND (T293N) and one with iDEND (R50P) syndrome. Three others with iDEND mutations (R201C, G53D, and V59M) remained neurologically normal at 5, 1, and 4 years of age, respectively, with early introduction of sulfonylurea. CONCLUSION: Overall, clinical presentation of KATP-NDM in Japanese patients was similar to those of other populations. Early introduction of sulfonylurea appeared beneficial in ameliorating neurological symptoms.

Phenotypic Variability and Newly Identified Mutations of the IVD Gene in Japanese Patients with Isovaleric Acidemia.

Isovaleric acidemia (IVA) is an autosomal recessive inborn error affecting leucine metabolism. It is caused by a deficiency in isovaleryl-CoA dehydrogenase (IVD), a mitochondrial matrix enzyme that catalyzes the oxidation of isovaleryl-CoA to 3-methylcrotonyl-CoA. IVD is a FAD-containing enzyme, consisting of four identical subunits. Clinical features of IVA include poor feeding, vomiting, lethargy, developmental delay, metabolic acidosis, and a characteristic "sweaty foot" odor. IVA is one of the target disorders for newborn screening by tandem mass spectrometry (MS/MS). The human IVD gene is located on chromosome 15q. To date, over 50 disease-causing mutations have been reported worldwide. In this study, we searched for IVD mutations in five Japanese patients with IVA (neonatal type, two patients; chronic intermittent type, two patients; and mild biochemical type, one patient). The diagnosis of IVA was confirmed by urinary organic acid analysis using gas chromatography and mass spectrometry. All coding exons and the flanking introns in the IVD gene were amplified by PCR and were directly sequenced. We thus identified six hitherto unknown mutations (p.G94D, p.E116K, p.M167T, p.L243P, p.L246P, and c.696+1G>T) and four previously reported (p.R53P, p.R395C, p.Y403C, and p.E411K) pathogenic mutations. All patients were compound heterozygotes, and each mutation was identified in a single patient. Pathogenicity of newly identified mutations was validated using computational programs. Among them, the p.M167T is believed to influence FAD binding, as the position 167 is present in one of the FAD-binding sites. Our results have illustrated the heterogeneous mutation spectrum and clinical presentation of IVA in the Japanese patients.

Does the spread of hepatitis B virus genotype A increase the risk of intrafamilial transmission in Japan?

Recently, the prevalence of genotype A in patients with acute hepatitis B virus (HBV) infection has markedly increased in Japan. We encountered a 1-year-old infant who was infected with HBV genotype A and became an HBV carrier. His grandfather was identified as an HBV carrier; however, the grandfather was not aware of chronic HBV infection. This was a case of intrafamilial transmission. In addition, the child's father developed acute hepatitis B within 1 month of the infant's diagnosis. Molecular analysis revealed that the HBV isolates from the grandfather, the infant, and the father had identical sequences that belonged to genotypes A2/Ae. Compared with other HBV genotypes, genotype A has a significant association with chronic outcome. Therefore, prolonging hepatitis can increase the risk of transmitting the virus without realizing. The at-risk strategy of hepatitis B vaccination, which has been adopted in Japan, cannot prevent such intrafamilial transmission. Universal vaccination in childhood is only one way to prevent young children from unexpected HBV infection.

A case of child-to-father transmission of hepatitis B virus in Japan: a rare infection route.

This report describes a rare horizontal transmission of hepatitis B virus (HBV) from an unvaccinated 6-year-old boy to his father. The father had been diagnosed with acute hepatitis B 1 month earlier; therefore, when the child visited the clinic with fever, he was screened for HBV markers and diagnosed as an asymptomatic carrier. Neither the child nor his father was vaccinated against HBV, whereas the child's mother and sister, having received the HBV vaccination as they were medical staff and a nursing student, respectively, tested negative for the hepatitis B surface antigen (HBsAg) and positive for anti-HBs. We performed a phylogenetic analysis of HBV in the child and his father, and identified 100% homologous strains of identical genotype C. At diagnosis, the father tested positive for IgM anti-hepatitis B core with a high titer, whereas the child tested negative for this marker. These data strongly indicated a child-to-father transmission. In this case, the HBV infection route was speculated as close contact including saliva-based transmission between the child and father, mainly attributed to their daily food habits. When clinicians diagnose patients with acute or chronic HBV infection, the household members should have been examined for HBV markers immediately. If some household members are susceptible to HBV infection, all members should be vaccinated against HBV.

Genetics of Congenital Isolated TSH Deficiency: Mutation Screening of the Known Causative Genes and a Literature Review.

CONTEXT: Congenital isolated TSH deficiency (i-TSHD) is a rare form of congenital hypothyroidism. Five genes (IGSF1, IRS4, TBL1X, TRHR, and TSHB) responsible for the disease have been identified, although their relative frequencies and hypothalamic/pituitary unit phenotypes have remained to be clarified. OBJECTIVES: To define the relative frequencies and hypothalamic/pituitary unit phenotypes of congenital i-TSHD resulting from single gene mutations. PATIENTS AND METHODS: Thirteen Japanese patients (11 boys and 2 girls) with congenital i-TSHD were enrolled. IGSF1, IRS4, TBL1X, TRHR, and TSHB were sequenced. For a TBL1X mutation (p.Asn382del), its pathogenicity was verified in vitro. For a literature review, published clinical data derived from 74 patients with congenital i-TSHD resulting from single-gene mutations were retrieved and analyzed. RESULTS: Genetic screening of the 13 study subjects revealed six mutation-carrying patients (46%), including five hemizygous IGSF1 mutation carriers and one hemizygous TBL1X mutation carrier. Among the six mutation carriers, one had intellectual disability and the other one had obesity, but the remaining four did not show nonendocrine phenotypes. Loss of function of the TBL1X mutation (p.Asn382del) was confirmed in vitro. The literature review demonstrated etiology-specific relationship between serum prolactin (PRL) levels and TRH-stimulated TSH levels with some degree of overlap. CONCLUSIONS: The mutation screening study covering the five causative genes of congenital i-TSHD was performed, showing that the IGSF1 defect was the leading genetic cause of the disease. Assessing relationships between serum PRL levels and TRH-stimulated TSH levels would contribute to predict the etiologies of congenital i-TSHD.

Comparison of brachial artery flow-mediated dilation in youth with type 1 and type 2 diabetes mellitus.

AIMS/INTRODUCTION: Brachial artery flow-mediated dilation (FMD) is a method of evaluating the function of vascular endothelial cells and is utilized for early diagnosis of atherosclerotic diseases. Only a few studies evaluated the risks for major vascular complications in youth with type 1 and 2 diabetes mellitus from the aspect of the early development of atherosclerosis. We studied whether there is a difference in vascular endothelial cell function between youth with type 1 and 2 diabetes mellitus. MATERIALS AND METHODS: We assessed %FMD of 24 patients with type 1 diabetes mellitus and 27 patients with type 2 diabetes mellitus aged 12-20 years along with glycated hemoglobin, lipid metabolism markers such as triglycerides, and inflammatory biomarkers such as total adiponectin levels in adolescent patients with type 1 or 2 diabetes mellitus. The significance of the difference in each factor between the type 1 and type 2 diabetes groups was assessed using Student's t-test. RESULTS: The %FMD was significantly lower in patients with type 2 diabetes. The body mass index and blood pressure were significantly higher, and total and high-molecular-weight adiponectin levels were significantly lower in patients with type 2 diabetes. %FMD significantly correlated with systolic blood pressure. CONCLUSIONS: The results suggest that youth with type 2 diabetes have more advanced damage of the vascular endothelium and therefore are at higher risk for major vascular complications. Therefore, monitoring the progression of atherosclerosis would also be beneficial in youth with diabetes mellitus, and measurement of FMD could be further warranted.

Urine screening for patients with developmental disabilities detected a patient with creatine transporter deficiency due to a novel missense mutation in SLC6A8.

Creatine transporter deficiency (CTD) is an example of X-linked intellectual disability syndromes, caused by mutations in SLC6A8 on Xq28. Although this is the second most frequent genetic cause of intellectual disabilities in Europe or America after Fragile X syndrome, information on the morbidity of this disease is limited in Japan. Using the HPLC screening method we have established recently, we examined samples of urine of 105 patients (73 males and 32 females) with developmental disabilities at our medical center. And we have found a family with three ID boys with a novel missense mutation in SLC6A8. This is the second report of a Japanese family case of CTD. A systematic diagnostic system of this syndrome should be established in Japan to enable us to estimate its frequency and treatment.

Steroid-sensitive nephrotic syndrome in two families.

Few reports of familial cases of steroid-sensitive nephrotic syndrome (SSNS) are available. Of 123 children with SSNS, four cases in two families are presented. Two sisters and a father and his daughter developed SSNS. The incidence of SSNS siblings in Japan seems to be similar to the incidence reported in other countries. SSNS in two generations is rare. To our knowledge, cases of SSNS in a parent and a child in Japan have not been reported.

Effects of leukocytosis and macrophage activation on anti-Thy 1.1 glomerulonephritis in the rat.

OBJECTIVE: In anti-Thy 1.1 proliferative glomerulonephritis (GN), glomerular infiltration of polymorphonuclear leukocytes (PMNs) reaches a peak level after 1 h and that of macrophages does so 24 h after induction. However, the roles of PMNs and macrophages in the pathogenesis of anti-Thy 1.1 GN remain unclear. We examined the effects on this model of leukocytosis induced by granulocyte colony-stimulating factor (G-CSF) and of macrophages stimulated by macrophage colony-stimulating factor (M-CSF). MATERIAL AND METHODS: Anti-Thy 1.1 GN was induced in male Wistar rats by intravenous injection of OX-7, a monoclonal antibody to the Thy 1 antigen. G-CSF (10 microg/kg/day), M-CSF (20 microg/kg/day) or vehicle was administered intraperitoneally for 7 days starting 24 h before the injection of OX-7. Histological examination of renal biopsy specimens was performed on Days 1, 5 and 14 after induction. RESULTS: Circulating and glomerular-infiltrating PMNs (RP-3-positive cells) were increased at Day 5 in G-CSF-treated rats compared with controls receiving vehicle, and glomerular mesangiolysis continued at Day 5. The number of proliferating cells positive for proliferating cell nuclear antigen at Day 5 and matrix scores at Day 14 were smaller in G-CSF-treated rats than in control rats. The mesangiolysis score was significantly higher in the G-CSF group than in the control group at Days 5 and 14, but not at Day 1. ED-1-positive cells were increased in number at Day 5 and matrix accumulation decreased at Day 14 in M-CSF-treated rats compared with controls. Serum creatinine level at Day 14 was lower in the M-CSF group, but not in the G-CSF group, compared with the control group. CONCLUSIONS: Activated macrophages may inhibit excess matrix accumulation and ameliorate the recovery of renal function, whereas leukocytosis inhibits the repair of mesangial cell injury in this model.