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Background Many patients with childhood idiopathic nephrotic syndrome are steroid-sensitive. Several genome-wide association studies have suggested a polygenic contribution, particularly in the HLA DR/DQ region and a locus including nephrin, but the etiology remains unclear. Anti-nephrin antibodies have recently been reported in both adults and children with biopsy proven minimal change disease (MCD), but the presence of anti-nephrin antibodies in Japanese childhood idiopathic nephrotic syndrome (INS) has not been investigated. Methods Anti-nephrin antibodies were measured by ELISA in paired plasma samples obtained from 14 Japanese pediatric patients with INS (male/female: 8/6), at onset (active disease) and following steroid monotherapy. Results The median age at the onset was 75.5 months (interquartile range (IQR): 45-113). Steroid sensitivity resulted in complete remission in 13 patients and almost complete remission in one patient after 4 weeks of glucocorticoid monotherapy. Circulating anti-nephrin antibodies were detected in seven of 14 patients during active disease. In all cases, anti-nephrin antibodies were significantly reduced following treatment concordant with clinical response. There were no differences between the positive and negative groups in pre-treatment parameters. Of the 13 patients who achieved complete remission, nine had at least one relapse during a median follow-up of 851 days (IQR: 808-973). There was also no significant difference in the relapse-free period after the onset between the two groups (P=0.658). Conclusions We identified circulating anti-nephrin antibodies in half of Japanese pediatric patients with INS at initial presentation, which is higher than has been previously reported in a North American cohort.

Oligomeganephronia (OMN) is a rare congenital anomaly involving the kidney and urinary tract, characterized by decreased number and compensatory hypertrophy of the nephron. It is caused by abnormal kidney development during the embryonic period, especially in patients with low birth weight; however, the actual etiology and clinical features remain unknown. We aim to reveal the clinical and pathological characteristics, treatment, and outcome.Ten patients diagnosed with OMN between 2013 and 2020 were retrospectively investigated. The data were presented as the median ± interquartile range, and statistical significance was set at p 0.05.The age at diagnosis was 14.1 years, the male-to-female ratio was 6:4, and only four cases were born with low birth weight. The estimated glomerular filtration rate (eGFR) was 62.2 mL/min/1.73 mAs few symptoms can lead to OMN discovery, most patients were found during urine screening at school. Kidney dysfunction was observed in all patients at the time of kidney biopsy. Proteinuria has been significantly reduced and the decline rate of eGFR might be improved by RAS inhibitors. "A higher resolution version of the Graphical abstract is available as Supplementary information".

Background and objectivesThe evident genotype–phenotype correlation shown by the X-linked Alport syndrome warrants the assessment of the impact of identified gene variants on aberrant splicing. We previously reported that single nucleotide variants (SNVs) in the last nucleotide of exons inCOL4A5cause aberrant splicing. It is known that the nucleotides located 2nd and 3rd to the last nucleotides of exons can also play an essential role in the first step of the splicing process. In this study, we aimed to investigate whether SNVs positioned 2nd or 3rd to the last nucleotide of exons inCOL4A5resulted in aberrant splicing.MethodsWe selected eight candidate variants: six from the Human Gene Variant Database Professional and two from our cohort. We performed anin-vitrosplicing assay and reverse transcription-polymerase chain reaction (RT-PCR) for messenger RNA obtained from patients, if available.ResultsThe candidate variants were initially classified into the following groups: three nonsense, two missense, and three synonymous variants. Splicing assays and RT-PCR for messenger RNA revealed that six of the eight variants caused aberrant splicing. Four variants, initially classified as non-truncating variants, were found to be truncating ones, which usually show relatively more severe phenotypes.ConclusionWe revealed that exonic SNVs positioned 2nd or 3rd to the last nucleotide of exons in theCOL4A5were responsible for aberrant splicing. The results of our study suggest that attention should be paid when interpreting the pathogenicity of exonic SNVs near the 5′ splice site.

Background Fabry disease is an X-linked lysosomal storage disorder caused by insufficient α-galactosidase A (GLA) activity resulting from variants in the GLA gene, which leads to glycosphingolipid accumulation and life-threatening, multi-organ complications. Approximately 50 variants have been reported that cause splicing abnormalities in GLA. Most were found within canonical splice sites, which are highly conserved GT and AG splice acceptor and donor dinucleotides, whereas one-third were located outside canonical splice sites, making it difficult to interpret their pathogenicity. In this study, we aimed to investigate the genetic pathogenicity of variants located in non-canonical splice sites within the GLA gene. Methods 13 variants, including four deep intronic variants, were selected from the Human Gene Variant Database Professional. We performed an in vitro splicing assay to identify splicing abnormalities in the variants. Results All candidate non-canonical splice site variants in GLA caused aberrant splicing. Additionally, all but one variant was protein-truncating. The four deep intronic variants generated abnormal transcripts, including a cryptic exon, as well as normal transcripts, with the proportion of each differing in a cell-specific manner. Conclusions Validation of splicing effects using an in vitro splicing assay is useful for confirming pathogenicity and determining associations with clinical phenotypes.