Dent disease in Poland: what we have learned so far?

PURPOSE: Dent disease (DD) is a rare tubulopathy characterized by proximal tubular dysfunction leading to chronic kidney disease (CKD). The aim of the study was to characterize patients with DD in Poland. METHODS: A retrospective analysis of a national cohort with genetically confirmed diagnosis. RESULTS: Of 24 males, all patients except one carried mutations in the CLCN5 gene; in one patient a mutation in the OCRL gene was disclosed. Molecular diagnosis was delayed 1 year on average (range 0-21 years). The most common features were tubular proteinuria (100%), hypercalciuria (87%), and nephrocalcinosis (56%). CKD (≤stage II) and growth deficiency were found in 45 and 22% of patients, respectively. Over time, a progression of CKD and persistence of growth impairment was noted. Subnephrotic and nephrotic proteinuria (20%) was found in most patients, but tubular proteinuria was assessed in only 67% of patients. In one family steroid-resistant nephrotic syndrome prompted a genetic testing, and reverse phenotyping. Five children (20%) underwent kidney biopsy, and two of them were treated with immunosuppressants. Hydrochlorothiazide and angiotensin-converting enzyme inhibitors were prescribed for a significant proportion of patients (42 and 37.5%, respectively), while supplemental therapy with phosphate, potassium, vitamin D (12.5% each), and alkali (4.2%) was insufficient, when compared to the percentages of patients requiring repletion. CONCLUSIONS: We found CLCN5 mutations in the vast majority of Polish patients with DD. Proteinuria was the most constant finding; however, tubular proteins were not assessed commonly, likely leading to delayed molecular diagnosis and misdiagnosis in some patients. More consideration should be given to optimize the therapy.

No major role for periconceptional folic acid use and its interaction with the MTHFR C677T polymorphism in the etiology of congenital anorectal malformations.

BACKGROUND: Both genetic and nongenetic factors are suggested to be involved in the etiology of congenital anorectal malformations (ARM). Maternal periconceptional use of folic acid supplements were inconsistently suggested to play a role in the prevention of ARM. Therefore, we investigated independent associations and interactions of maternal periconceptional folic acid supplement use and the infant and maternal MTHFR (methylenetetrahydrofolate reductase) C677T polymorphisms with the risk of ARM and subgroups of ARM. METHODS: A case-control study was conducted among 371 nonsyndromic ARM cases and 714 population-based controls born between 1990 and 2012 using maternal questionnaires and DNA samples from mother and child. Cases were treated for ARM at departments of Pediatric Surgery of the Radboud university medical center, Sophia Children's Hospital-Erasmus MC Rotterdam, and the University Medical Center Groningen in The Netherlands and hospitals throughout Germany. RESULTS: No association with folic acid use was present (odds ratio = 1.1; 95% confidence interval: 0.8-1.4) for ARM as a group. Infant and maternal MTHFR C677T polymorphisms were weakly associated with isolated ARM in particular. Lack of folic acid supplement use in combination with infants or mothers carrying the MTHFR C677T polymorphism did not seem to increase the risk of ARM or subgroups of ARM. The relative excess risks due to interaction did not clearly indicate interaction on an additive scale either. CONCLUSION: This first study investigating interactions between periconceptional folic acid supplement use and infant and maternal MTHFR C677T polymorphisms in the etiology of ARM did not provide evidence for a role of this gene-environment interaction.

Phenotype severity in the bladder exstrophy-epispadias complex: analysis of genetic and nongenetic contributing factors in 441 families from North America and Europe.

OBJECTIVE: To identify genetic and nongenetic risk factors that contribute to the severity of the bladder exstrophy-epispadias complex (BEEC). STUDY DESIGN: Patients with BEEC from North America (n = 167) and Europe (n = 274) were included. The following data were collected: associated anomalies, parental age at conception, mode of conception, periconceptional folic acid supplementation, maternal risk factors during pregnancy, and environmental risk factors. The patients were divided into 3 subgroups according to phenotype severity: (i) mild, epispadias (n = 43); (ii) intermediate, classic bladder exstrophy (n = 366); and (iii) severe, cloacal exstrophy (n = 31). These subgroups then were compared with identify factors that contribute to phenotype severity. RESULTS: Males were overrepresented in all subgroups. A relatively high prevalence of cleft lip, with or without cleft palate, was observed. Maternal smoking and medical radiation during the first trimester were associated with the severe cloacal exstrophy phenotype. Compliance with periconceptional folic acid supplementation was associated with the mildest phenotype (epispadias). CONCLUSIONS: Periconceptional folic acid supplementation appears to prevent the development of the severe phenotype of BEEC.

MTHFR 677 TT genotype in a mother and her child with Down syndrome, atrioventricular canal and exstrophy of the bladder: implications of a mutual genetic risk factor?

Apart from Husmann and Vandersteen [in: Gearhart JP, Matthews R (eds) The Epispadias-Exstrophy Complex. Kluwer, New York, pp 199-206, 1999], we report only the second case of Down syndrome (DS) associated with exstrophy of the bladder (EB). Besides the appearance of DS, the newborn exhibited a complete atrioventricular canal (CAVC) and classical EB, including diastases of the symphysis, an epispadic penis and an open bladder plate. Despite current recommendations, the mother had not supplemented her intake of folic acid during the periconceptional period. In a comparable case, Al-Gazali et al. (Am J Med Genet 103:128-132, 2001) found the homozygous 677T allele of the methylenetetrahydrofolate (MTHFR) gene 677C-->T polymorphism in a mother and her child with DS and cervical meningomyelocele. They found that the mother, who also had not supplemented her folic acid intake, had a secondarily altered folate status with an increased homocysteine level, suggesting that the homozygous TT mutation in the MTHFR gene in both mother and her child had contributed to the presentation of DS and a neural tube defect. The combined clinical findings of the present case and the observations of Al-Gazali et al. led us to investigate the 677C-->T polymorphism in our mother-child pair. Likewise we found that mother and child were homozygous for the mutant 677T allele. Our findings support the suggestion of Al-Gazali et al. that the MTHFR 677TT could be a mutual genetic risk factor for the co-occurrence of trisomy 21 and midline defects, the risk of which may be reduced by periconceptional folic acid supplementation.