Combined Alport syndrome and Klinefelter syndrome.

To date, there have been a very limited number of case reports on combined Alport syndrome (AS) and Klinefelter syndrome (KS). We herein describe the case of a 9-month-old boy diagnosed with concomitant AS and KS. KS was detected on chromosomal analysis of the amniotic fluid, and hematuria/proteinuria was identified in urinary screening at 6 months of age. Renal biopsy indicated AS, with complete deficit of the α5 chain of type IV collagen in the glomerular basement membranes. On genetic analysis for AS, de novo homozygote mutation (c.3605-2a > c) was seen in the gene encoding α5 chain of type IV collagen (COL4A5) on the X chromosomes of maternal origin. This is the first case report of combined AS and KS diagnosed during infancy, and it indicates the need to consider the concurrent existence of these two disorders in infants with urine abnormalities, even in the absence of a family history.

X-linked Alport syndrome caused by splicing mutations in COL4A5.

BACKGROUND AND OBJECTIVES: X-linked Alport syndrome is caused by mutations in the COL4A5 gene. Although many COL4A5 mutations have been detected, the mutation detection rate has been unsatisfactory. Some men with X-linked Alport syndrome show a relatively mild phenotype, but molecular basis investigations have rarely been conducted to clarify the underlying mechanism. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In total, 152 patients with X-linked Alport syndrome who were suspected of having Alport syndrome through clinical and pathologic investigations and referred to the hospital for mutational analysis between January of 2006 and January of 2013 were genetically diagnosed. Among those patients, 22 patients had suspected splice site mutations. Transcripts are routinely examined when suspected splice site mutations for abnormal transcripts are detected; 11 of them showed expected exon skipping, but others showed aberrant splicing patterns. The mutation detection strategy had two steps: (1) genomic DNA analysis using PCR and direct sequencing and (2) mRNA analysis using RT-PCR to detect RNA processing abnormalities. RESULTS: Six splicing consensus site mutations resulting in aberrant splicing patterns, one exonic mutation leading to exon skipping, and four deep intronic mutations producing cryptic splice site activation were identified. Interestingly, one case produced a cryptic splice site with a single nucleotide substitution in the deep intron that led to intronic exonization containing a stop codon; however, the patient showed a clearly milder phenotype for X-linked Alport syndrome in men with a truncating mutation. mRNA extracted from the kidney showed both normal and abnormal transcripts, with the normal transcript resulting in the milder phenotype. This novel mechanism leads to mild clinical characteristics. CONCLUSIONS: This report highlights the importance of analyzing transcripts to enhance the mutation detection rate and provides insight into genotype-phenotype correlations. This approach can clarify the cause of atypically mild phenotypes in X-linked Alport syndrome.

Milder clinical aspects of X-linked Alport syndrome in men positive for the collagen IV α5 chain.

X-linked Alport syndrome is caused by mutations in the COL4A5 gene encoding the type IV collagen α5 chain (α5(IV)). Complete absence of α5(IV) in the renal basal membrane is considered a pathological characteristic in male patients; however, positive α5(IV) staining has been found in over 20% of patients. We retrospectively studied 52 genetically diagnosed male X-linked Alport syndrome patients to evaluate differences in clinical characteristics and renal outcomes between 15 α5(IV)-positive and 37 α5(IV)-negative patients. Thirteen patients in the α5(IV)-positive group had non-truncating mutations consisting of nine missense mutations, three in-frame deletions, and one splice-site mutation resulting in small in-frame deletions of transcripts. The remaining two showed somatic mutations with mosaicism. Missense mutations in the α5(IV)-positive group were more likely to be located before exon 25 compared with missense mutations in the α5(IV)-negative group. Furthermore, urinary protein levels were significantly lower and the age at onset of end-stage renal disease was significantly higher in the positive group than in the negative group. These results help to clarify the milder clinical manifestations and molecular characteristics of male X-linked Alport syndrome patients expressing the α5(IV) chain.

A patient with autosomal recessive Alport syndrome due to segmental maternal isodisomy.

We report the case of a 22-year-old male with autosomal recessive Alport syndrome. Molecular analysis showed that this patient has a homozygous missense (NM_000091.4:c.3266G>A) Gly1089Asp mutation in the COL4A3 gene. The proband inherited the mutation from his heterozygous carrier mother, whereas the father carried only wild-type alleles. We performed comparative genome hybridization and single-nucleotide polymorphism microarray analyses and confirmed that there was partial maternal isodisomy.

SLC26A3 gene analysis in patients with Bartter and Gitelman syndromes and the clinical characteristics of patients with unidentified mutations.

We analyzed the SLC26A3 gene in patients with a clinical diagnosis of Bartter and Gitelman syndromes in whom genetic diagnoses could not be determined. We also examined the genetic and clinical characteristics of patients for whom genetic proof could not be obtained. The present study included 10 patients. With regard to genetic characteristics, 1 patient harbored a heterozygous mutation in the SLC12A3 gene (c.2573T>A, p.L858H), which was also reported in a previous report. With regard to clinical characteristics, 3 patients had abnormalities that were identified incidentally during medical examinations and other illnesses and 1 patient had polyhydramnios. One case of nephrocalcinosis was also noted. Eight patients were of below average height. Although we analyzed the SLC26A3 gene in these 10 patients, none were found to have pathological mutations. Investigation of the outcomes of these cases showed that examination findings had normalized and medication was no longer necessary for 3 patients, whereas hypokalemia and metabolic alkalosis were observed in another patient only in the presence of acute disease. We concluded that few patients develop illnesses because of SLC26A3 mutations. Other disease-related genes may also be involved. Although hypokalemia and metabolic alkalosis are clinical characteristics of Bartter and Gitelman syndromes, many other conditions also present such symptoms, and thus, differential diagnosis is of paramount importance.

Renal transplantations from parents to siblings with autosomal recessive Alport syndrome caused by a rearrangement in an intronic antisense Alu element in the COL4A3 gene led to different outcomes.

Two siblings with autosomal recessive Alport syndrome (ARAS) obtained renal transplants from their consanguineous parents. Their COL4A3 mRNA transcripts were disrupted by a 139 bp intronic sequence between exon 48 and 49, which was derived from an antisense Alu element in this intron. The new amino acid sequence from the cryptic exon was terminated by a stop codon at the 1511th codon, resulting in the loss of 76 % α3(IV)NC1. This is the first case report of kidney transplantations between ARAS-homozygous siblings and their heterozygous parents. The brother experienced acute rejection just after transplantation and post-transplantation anti-glomerular basement membrane (GBM) nephritis, whereas the sister has experienced no problems to date. The anti-GBM nephritis could have resulted from the acute rejection. The COL4A3 gene heterozygous mutated parents, who are possibly at risk for thin basement membrane disease, have maintained their renal functions without urinary abnormalities after renal transplantation to date.

Metabolomics analysis of umbilical cord blood clarifies changes in saccharides associated with delivery method.

BACKGROUND: A metabolomic approach using umbilical cord blood from infants at birth has not been studied widely yet. AIM: We examined changes in metabolite levels in umbilical cord blood at birth via gas chromatography/mass spectrometry (GC/MS)-based metabolomics, with the aim of achieving a detailed understanding of fetal stress during labor. STUDY DESIGN: All procedures were reviewed and approved by the Institutional Review Board of Kobe University School of Medicine. This was a cohort study of pregnant women based in Palmore Hospital, which is located in an urban area of Japan, and was carried out between December 2010 and May 2011. SUBJECT: Umbilical cord arterial blood samples were obtained from 41 infants immediately after delivery. OUTCOME MEASURES: Metabolites in the blood samples were measured using GC/MS to investigate whether the delivery method (spontaneous onset of labor, induction of labor or elective cesarean section) affected the metabolite profile in umbilical cord blood. RESULTS: Elective cesarean section without labor led to lower levels of isoleucine, fructose, mannose, glucose, allose, glucuronic acid, inositol and cysteine in comparison with vaginal delivery following spontaneous labor and without medication. CONCLUSION: It is proposed that the stress associated with labor be involved in alterations in the levels of metabolites, particularly saccharides such as glucose, in umbilical cord blood.