Rhian L. Clissold

HNF1B-associated renal and extra-renal disease—an expanding clinical spectrum

Heterozygous mutations in the gene that encodes the transcription factor hepatocyte nuclear factor 1β (HNF1B) represent the most common known monogenic cause of developmental kidney disease. Renal cysts are the most frequently detected feature of HNF1B-associated kidney disease; however, other structural abnormalities, including single kidneys and renal hypoplasia, and electrolyte abnormalities can also occur. Extra-renal phenotypes might also be observed; consequently, HNF1B-associated disease is considered a multi-system disorder. Other clinical features include early-onset diabetes mellitus, pancreatic hypoplasia, genital tract malformations, abnormal liver function and early-onset gout. Heterozygous mutations in the coding region or splice sites of HNF1B, and complete gene deletion, each account for ∼50% of all cases of HNF1B-associated disease, respectively, and often arise spontaneously. There is no clear genotype–phenotype correlation, consistent with haploinsufficiency as the disease mechanism. Data from animal models suggest that HNF1B has an important function during several stages of nephrogenesis; however, the precise signalling pathways remain to be elucidated. This Review discusses the genetics and molecular pathways that lead to disease development, summarizes the reported renal and extra-renal phenotypes, and identifies areas for future research in HNF1B-associated disease.

Chromosome 17q12 microdeletions but not intragenic HNF1B mutations link developmental kidney disease and psychiatric disorder

Heterozygous mutations of the HNF1B gene are the commonest known monogenic cause of developmental kidney disease. Half of patients have a deletion (approximately 1.3 Mb) of chromosome 17q12, encompassing HNF1B plus 14 additional genes. This 17q12 deletion has been linked with an increased risk of neurodevelopmental disorders, such as autism. Here we compared the neurodevelopmental phenotype of 38 patients with HNF1B-associated renal disease due to an intragenic mutation in 18 patients or due to 17q12 deletion in 20 patients to determine whether haploinsufficiency of HNF1B is responsible for the neurodevelopmental phenotype. Significantly, brief behavioral screening in children with the deletion showed high levels of psychopathology and its impact. Eight individuals (40%) with a deletion had a clinical diagnosis of a neurodevelopmental disorder compared to none with an intragenic mutation. The 17q12 deletions were also associated with more autistic traits. Two independent clinical geneticists were able to predict the presence of a deletion with a sensitivity of 83% and specificity of 79% when assessing facial dysmorphic features as a whole. Thus, the 17q12 deletions but not HNF1B intragenic mutations are associated with neurodevelopmental disorders. Hence, the HNF1B gene is not involved in the neurodevelopmental phenotype of these patients. Nephrologists need to be aware of this association to ensure appropriate referral to psychiatric services.

Sociodemographic, Psychologic Health, and Lifestyle Outcomes in Young Adults on Renal Replacement Therapy

BACKGROUND AND OBJECTIVES Young adults receiving RRT face additional challenges in life. The effect of established kidney failure on young adulthood is uncertain. We aimed to establish the psychosocial and lifestyle status of young adults receiving RRT. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Our study was a systematic review and meta-analysis of 16-30-year olds receiving RRT compared with the general population. We selected randomized, controlled trials; cohort studies; or cross-sectional studies without language restriction and extracted proportions of sociodemographic and lifestyle outcomes or validated psychologic health tests producing quality of life, wellbeing, and self-esteem scores. We undertook random effects meta-analysis. RESULTS There were 60 studies with a total of 15,575 participants. Studies were largely single-center cross-sectional studies of those transplanted in childhood. Compared with healthy peers, young adults on RRT had lower quality of life, which was worse for patients on dialysis (seven studies: standardized mean difference, -1.01; 95% confidence interval [95% CI], -1.32 to -0.70) compared with patients with transplants (nine studies: standardized mean difference, -0.42; 95% CI, -0.64 to -0.20). They were more likely to be unemployed (seven studies: relative risk, 1.89; 95% CI, 1.47 to 2.44) and live in the family home (two studies: relative risk, 1.84; 95% CI, 1.40 to 2.43). They were less likely to be married or have a partner (four studies: relative risk, 0.71; 95% CI, 0.53 to 0.95). Higher education (three studies: relative risk, 1.05; 95% CI, 0.73 to 1.51), alcohol abstinence (three studies: relative risk, 1.96; 95% CI, 0.84 to 4.67), and smoking status (two studies: relative risk, 0.72; 95% CI, 0.36 to 1.44) did not differ. Results were limited by high heterogeneity and a small evidence base, biased toward surviving patients. CONCLUSIONS Established kidney failure is associated with lower quality of life in young people and limited employment, independence, and relationships compared with healthy peers. PODCAST This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2017_10_19_CJASNPodcast_17_12_.mp3.

Comment on Dubois-Laforgue et al. Diabetes, Associated Clinical Spectrum, Long-term Prognosis, and Genotype/Phenotype Correlations in 201 Adult Patients With Hepatocyte Nuclear Factor 1B (HNF1B) Molecular Defects. Diabetes Care 2017;40:1436-1443.

We read with interest the large and impressive study by Dubois-Laforgue et al. (1) describing the phenotype, long-term follow-up, and genotype/phenotype correlations in 201 adults with hepatocyte nuclear factor 1B (HNF1B)-associated disease. They report that patients with an HNF1B mutation have a worse renal prognosis than those with a 17q12 deletion, as they had a higher frequency of chronic kidney disease stages 3–4/end-stage renal disease and a lower median estimated glomerular filtration rate (eGFR) at follow-up (42.5 vs. 75 mL/min/1.73 m2, respectively; P = 0.008). The article did not comment on the fact that similar results have previously been found in two …

Young adults’ perspectives on living with kidney failure: a systematic review and thematic synthesis of qualitative studies

Introduction Young adults fare worse than younger adolescents or older adults on a broad range of health indicators. Those with a chronic illness such as renal failure are a particularly vulnerable group, who experience poor outcomes compared with both children and older adults. Understanding how being in receipt of renal replacement therapy (RRT) affects the lives of young adults might help us to better prepare and support these individuals for and on RRT, and improve outcomes. This study aimed to synthesise research describing young adults’ experiences of the psychosocial impact of kidney failure and RRT. Design A systematic literature review identified qualitative research reporting the perspectives of people aged 16–30 years receiving RRT on the psychosocial impact of renal failure. Electronic databases (including Medline/EMBASE/PsycINFO/ASSIA) were searched to November 2017 for full-text papers. The transparency of reporting of each study was assessed using the Consolidated Criteria for Reporting Qualitative Health Research (COREQ) framework. Quality was assessed using the Critical Appraisal Skills Programme qualitative checklist. An inductive thematic synthesis was undertaken. Participants Seven studies from five different countries were included, comprising 123 young adults receiving RRT. Results Comprehensiveness of reporting was variable: studies reported 9–22 of the 32 COREQ-checklist items. Three global themes about the impact of kidney failure on young adults were identified: (1) difference desiring normality, (2) thwarted or moderated dreams and ambitions, and (3) uncertainty and liminality. These reflected five organising themes: (1) physical appearance and body image, (2) activity and participation, (3) educational disruption and underachievement, (4) career ambitions and employment difficulties, and (5) social isolation and intimate relationships. Conclusions Across different countries and different healthcare settings, young adults on RRT experience difference and liminality, even after transplantation. Tailored social and psychological support is required to allow young adults to experience wellness while in receipt of RRT, and not have life on hold.

HNF1B Genetic Testing In a Turkish Cypriot Population with a High Incidence of Familial Kidney Disease

Rhian L Clissold1,2*, D Deren Oygar3, Daniel P Gale4, Coralie Bingham2 and Guy H Neild3 1University of Exeter Medical School, RILD Level 3, Barrack Road, Exeter, Devon, EX2 5DW, UK 2Exeter Kidney Unit, Royal Devon and Exeter Hospital, Barrack Road, Exeter, Devon, EX2 5DW, UK 3Nephrology Department, Nicosia State Hospital, Nicosia, North Cyprus 4UCL Centre for Nephrology, Royal Free Campus, London, NW3 2PF, UK

Assessment of the HNF1B Score as a Tool to Select Patients for HNF1B Genetic Testing

Background/Aims: Diagnosing hepatocyte nuclear factor 1β (HNF1B)-related disease is a challenging task due to the phenotypic variability and frequent absence of a family history. An HNF1B score has recently been developed to help select appropriate patients for genetic testing with a negative predictive value (NPV) of 99%. We aimed at testing the clinical utility of this score in a large number of referrals for HNF1B genetic testing to the UK diagnostic testing service for the HNF1B gene. Methods: An HNF1B score was assigned for 686 UK referrals for HNF1B genetic testing using clinical information available at referral. The performance of the score was evaluated by receiver-operating characteristic curve analysis. The relative discriminatory ability of different clinical features for making a genetic diagnosis of HNF1B-related disease were estimated in the UK dataset alone and pooled with French data. Results: The HNF1B score discriminated between patients with and without a mutation reasonably well with an area under the curve of 0.72. Applying the suggested cut-off score of ≥8 gave a NPV of 85%. In a pooled analysis, antenatal renal abnormalities, renal hyperechogenicity and cysts were discriminatory in children, whereas renal hypoplasia and cysts were discriminatory in adults. Pancreatic abnormalities were discriminatory in both, whereas other extra-renal characteristics had a large effect size only in adults. Conclusion: The HNF1B score was discriminatory for HNF1B mutations in a large cohort of individuals tested in a single UK centre. The lower NPV (85 vs. 99%) reduces its clinical utility in selecting patients for HNF1B genetic testing, although validation in a prospective cohort is required.

Exocrine pancreatic dysfunction is common in hepatocyte nuclear factor 1β–associated renal disease and can be symptomatic

Abstract Background Heterozygous mutations in the HNF1B gene are the most common monogenic cause of developmental kidney disease. Extrarenal phenotypes frequently occur, including diabetes mellitus and pancreatic hypoplasia; the latter is associated with subclinical exocrine dysfunction. We measured faecal elastase-1 in patients with HNF1B-associated disease regardless of diabetes status and assessed the degree of symptoms associated with pancreatic exocrine deficiency. Methods Faecal elastase-1 was measured in 29 patients with a known HNF1B mutation. We defined a low faecal elastase-1 concentration based on the 2.5 percentile of 99 healthy control individuals (410 μg/g stool). Symptoms related to pancreatic exocrine dysfunction were assessed and a subset of the HNF1B cohort (n  =  6) underwent pancreatic imaging. Results Faecal elastase-1 was below the 2.5 percentile of the control cohort in 18/29 (62%) patients with HNF1B-associated renal disease. A total of 8/29 (28%) had a measurement suggestive of exocrine pancreatic insufficiency at  <200 μg/g stool; of these, 3 suffered with abdominal pain, loose stools and/or unintentional weight loss. All three experienced symptomatic improvement and weight gain after commencing pancreatic enzyme replacement therapy. Faecal elastase-1 was low in 7/15 (47%) HNF1B patients without diabetes compared with 11/14 (79%) of those with diabetes (P  =  0.1). Conclusions Faecal elastase-1 deficiency is a common feature of HNF1B-associated renal disease even when diabetes is not present and pancreatic exocrine deficiency may be more symptomatic than previously suggested. Faecal elastase-1 should be measured in all patients with known HNF1B-associated disease complaining of chronic abdominal pain, loose stools or unintentional weight loss. The discovery of a low faecal elastase-1 concentration in individuals with developmental kidney disease of uncertain cause should prompt referral for HNF1B genetic testing.