Analysis of the ratio of urinary beta-2-microglobulin to total protein concentration in children with isolated tubulointerstitial disease.

BACKGROUND: Proteinuria is broadly classified into glomerular and tubular proteinuria. Urinary beta-2-microglobulin (ß2-MG) is known as a marker for detecting tubulointerstitial diseases. However, tubulointerstitial damage can also lead to an increase in urinary ß2-MG level in some patients with glomerular diseases. This study aimed to determine the ratio of urinary ß2-MG to total protein (TP) concentration in patients with both isolated tubulointerstitial and glomerular disease. METHODS: This multicenter, retrospective study included children with Dent disease or lupus nephritis in five facilities. Their urinary ß2-MG levels were > 1000 µg/L. Urinary ß2-MG and TP concentrations were obtained, and the ratio of urinary ß2-MG to TP concentration (µg/mg) was calculated. The Mann-Whitney U test was performed to compare this ratio between these children. The optimal cutoff value of the ratio for considering the presence of glomerular disease was obtained from the receiver operating characteristic (ROC) curve. RESULTS: We obtained information on 23 children with Dent disease and 14 children with lupus nephritis. The median ratios of urinary ß2-MG to TP concentrations in children with Dent disease and lupus nephritis were 84.85 and 1.59, respectively. The ROC curve yielded the optimal cutoff value of this ratio for distinguishing between these diseases, and the cutoff value was found to be 22.3. CONCLUSION: In children with tubulointerstitial diseases, the urinary ß2-MG concentration may be approximately 8.5% of the TP concentration. The possibility of presenting with glomerular disease should be considered in patients with a ratio of urinary ß2-MG to TP concentration of < 22.3 (µg/mg).

An infant case of pseudohypoaldosteronism type1A caused by a novel NR3C2 variant.

Pseudohypoaldosteronism type1A (PHA1A) is the renal form of pseudohypoaldosteronism with autosomal dominant inheritance. PHA1A is caused by haploinsufficiency of the mineralocorticoid receptor, which is encoded by NR3C2. We encountered an infant who was diagnosed with PHA1A due to hyponatremia, hyperkalemia, and poor weight gain in the neonatal period. She carried a novel heterozygous mutation (NM_000901.5: c.1757 + 1 G > C) in the splice donor site of IVS-2 in NR3C2.

A case with neonatal hyperinsulinemic hypoglycemia: It is a characteristic complication of Sotos syndrome.

Sotos syndrome (SoS, OMIM #117550) is an overgrowth syndrome. Deletions or intragenic mutations of the NSD1 , which is located at chromosome 5q35, are responsible for more than 75% of SoS. Conventionally, neonatal hypoglycemia was reported briefly as one of the infrequent symptoms of SoS. However, Matsuo et al. published a report describing five patients with SoS who presented with transient hyperinsulinemic hypoglycemia (HIH) in the neonatal period. We report on an additional patient of SoS, who presented transient HIH in the neonatal period. All of this patient and previous patients have microdeletions at the 5q35 chromosome. Therefore, we examined the following three in considering the possibility that other factor than NSD1 caused HIH. 1) This patient had no mutation of four currently known HIH related genes, ABCC8, KCNJ11, GLUD1, and GCK. 2) He had no further deletion than commonly observed region encompassing NSD1 by comparative genomic hybridization to DNA microarrays. 3) He had no mutation in the 5q35 region in the non-deleted chromosome using exsome sequence analysis. In conclusion, our patient supported that HIH could be one of the characteristic symptoms of SoS in the neonatal period, and could be useful for early diagnosis.

Clinical characterization and identification of duplication breakpoints in a Japanese family with Xq28 duplication syndrome including MECP2.

Xq28 duplication syndrome including MECP2 is a neurodevelopmental disorder characterized by axial hypotonia at infancy, severe intellectual disability, developmental delay, mild characteristic facial appearance, epilepsy, regression, and recurrent infections in males. We identified a Japanese family of Xq28 duplications, in which the patients presented with cerebellar ataxia, severe constipation, and small feet, in addition to the common clinical features. The 488-kb duplication spanned from L1CAM to EMD and contained 17 genes, two pseudo genes, and three microRNA-coding genes. FISH and nucleotide sequence analyses demonstrated that the duplication was tandem and in a forward orientation, and the duplication breakpoints were located in AluSc at the EMD side, with a 32-bp deletion, and LTR50 at the L1CAM side, with "tc" and "gc" microhomologies at the duplication breakpoints, respectively. The duplicated segment was completely segregated from the grandmother to the patients. These results suggest that the duplication was generated by fork-stalling and template-switching at the AluSc and LTR50 sites. This is the first report to determine the size and nucleotide sequences of the duplicated segments at Xq28 of three generations of a family and provides the genotype-phenotype correlation of the patients harboring the specific duplicated segment.

Methylxanthines inhibit late-onset circulatory collapse in preterm infants.

BACKGROUND: Several drugs, when used chronically in very preterm infants, are considered to be associated with the development of late-onset circulatory collapse (LCC), which can lead to neurodevelopmental impairment. Despite its clinical importance, conclusive risk factors for LCC have yet to be identified. The aim of the present study was to investigate the relationship between LCC and diuretics, methylxanthines, levothyroxine, and sodium chloride. METHODS: Infants born at <28 weeks gestational age were enrolled and divided into two groups: the LCC group and the non-LCC group. Use of diuretics, methylxanthines, or levothyroxine, and the sodium intake in each infant were recorded. We then determined if these represented primary risk factors associated with the development of LCC, using multivariate analysis to exclude confounding factors. RESULTS: Thirty-seven preterm infants were eligible for this study. LCC developed in 10 infants; 27 infants did not develop the disease. Only methylxanthine was significantly associated with a decrease in the incidence of LCC (odds ratio, 0.04; P < 0.05). We also observed a significant positive correlation between sodium intake and the period from diuretic treatment to LCC onset. CONCLUSIONS: Methylxanthine use was significantly associated with LCC onset. Diuretics may have the ability to provoke LCC through sodium wasting, resulting in a negative balance of the electrolyte. The incidence of LCC could be lowered by paying particular attention to infants' sodium balance, and by aggressive methylxanthine treatment.

Prevalence of hepatitis E virus infection in Japanese children.

BACKGROUND: Recently, sporadic cases of acute hepatitis and fulminant hepatitis caused by hepatitis E virus (HEV) have been reported in Japan. However, few reports have addressed the issue of HEV infection during childhood. METHODS: This study included 5 patients with fulminant hepatitis, 30 patients with acute hepatitis, and 309 patients without history of hepatic dysfunction or hepatitis in childhood as control. RNA was extracted from each serum sample, and HEV specific reverse-transcriptase polymerase chain reaction was performed. Anti-HEV immunoglobulin (Ig)M and IgG were measured by enzyme-linked immunoadsorbent assay. RESULTS: HEV RNA, anti-HEV IgM, and anti-HEV IgG were not detected in the sera of any of the five patients with fulminant hepatitis. In the 30 patients with acute hepatitis, only one (3.3%) was positive for anti-HEV IgG, and all were negative for anti-HEV IgM and HEV RNA. Of the 309 control patients, 8 (2.6%) were positive for anti-HEV IgG, and 2 (0.6%) were positive for anti-HEV IgM, respectively. CONCLUSION: The result of patients with fulminant hepatitis suggests that HEV is an unlikely cause of fulminant hepatitis in children. However, the detection rate of anti-HEV IgG shows that a history of HEV infection is not so rare among children in Japan.