Dominique Chauveau

Clinical Spectrum Associated with Hepatocyte Nuclear Factor-1β Mutations

Context Maturity-onset diabetes of the young type 5 (MODY5) is an uncommon variant of a dominantly inherited disease associated with mutations in the hepatocyte nuclear factor-1 (HNF-1) gene. We know little about its spectrum except that it may include urogenital abnormalities. Contribution This multicenter study describes 8 probands with MODY5 and known nondiabetic kidney disease and 5 offspring. Each proband had a different mutation in the HNF-1 gene. Probands and offspring had various renal abnormalities, including dysplastic kidneys and renal cysts. Some also had genital tract abnormalities, pancreatic atrophy, and abnormal liver enzyme levels. Implications Maturity-onset diabetes of the young type 5 is genetically and phenotypically heterogeneous. The Editors The prevalence of diabetes mellitus is estimated to be 6% to 7% in western industrialized countries; type 2 diabetes mellitus accounts for 90% of the cases (1). Maturity-onset diabetes of the young (MODY) is defined by the occurrence, typically before age 25 years, of nonketotic diabetes mellitus due to a primary defect of insulin secretion, along with autosomal dominant inheritance. With the exception of MODY2, which is due to mutations in the glucokinase gene, the identified MODY subtypes are related to mutations of transcription factor genes: hepatocyte nuclear factor-4 (HNF-4) for MODY1, HNF-1 for MODY3, insulin promoter factor-1 for MODY4, HNF-1 for MODY5, and neurogenic differentiation factor-1 for MODY6. The subtypes of MODY may account for 2% to 5% cases of type 2 diabetes, with types 3 and 2 representing 65% and 15% of these cases, respectively. The other subtypes of MODY are thought to be rare (2). Maturity-onset diabetes of the young type 5 was initially described in a Japanese family as the association of early-onset diabetes and nephropathy (3). Heterogeneous phenotypes, including diabetes, renal abnormalities, and genital malformations, were subsequently described through isolated case reports in white and Japanese populations (3-16). Currently, all but 2 families (6, 16) with MODY5 demonstrated autosomal dominant inheritance of private mutations. In our report, using a standardized evaluation, we describe clinical and genetic findings in 13 patients from 8 unrelated families with novel HNF-1 mutations. Detailed phenotypic analysis underlines the systemic spectrum of the disease and its wide variability, leading to different modes of presentation. We also confirm that MODY5 may occur because of de novo mutation in HNF-1. These findings may help to define criteria for HNF-1 gene testing. Methods Patients Participants were recruited from the patients of 2 departments of diabetes, 1 internal medicine department, and 1 nephrology department, on the basis of the following clinical characteristics: 1) diabetes (fasting plasma glucose level 7.0 mmol/L [126 mg/dL]), suggesting a MODY phenotype if diabetes occurred before 40 years of age, if the patient was not obese (body mass index < 30 kg/m2), and the patient did not have islet-cell antibodies and glutamic acid decarboxylase autoantibodies; 2) impaired renal function (creatinine clearance < 1.34 mL/s [<80 mL/min]) without diabetic retinopathy and albumin excretion greater than 0.5 g/d (17); and 3) kidney structural abnormalities (reduced kidney size, presence of cysts, or both). A family history of diabetes was not a criterion. A total of 20 unrelated white patients were identified from clinic lists and screened for HNF-1 mutation: 13 men and 7 women with a mean (sd) age of 26 8 years, a mean body mass index of 23.4 2.7 kg/m2 at onset of diabetes, and functional and structural renal abnormalities at presentation. The Ethics Committee of Necker Hospital, Paris, France, approved the study, and all participants gave written informed consent. Clinical Evaluation Clinical history of diabetes mellitus and renal involvement were recorded by using a standardized examination of the patients and their relatives. Creatinine clearance was calculated according to the Cockcroft-Gault formula (18). Imaging studies of the kidneys, consisting of ultrasonography and intravenous urography or computed tomography, and renal biopsy specimens were reviewed by a nephrologist and a renal pathologist. Genital tract abnormalities were assessed by ultrasonography. Endogenous insulin secretion was assessed by measuring C-peptide plasma concentration (Bio-Rad Specific C-Peptide, Bio-Rad, Marne la Coquette, France) before and 6, 10, and 15 minutes after intravenous injection of 1 mg of glucagon (19). Pancreas structure was assessed by computed tomography. Pancreas exocrine function was evaluated by measuring fecal fat excretion and elastase concentration (Schebo-Biotech, Guiessen, Germany). Liver biopsy was performed in 3 patients whose liver test results were persistently abnormal. Mutation Analysis of the HNF-1 Gene Genomic DNA was extracted from peripheral blood samples by standard procedures. The minimal promoter, the coding region of the 9 exons, and exon-intron boundaries of the HNF-1 gene were screened for mutations by direct sequencing as previously described (3). Direct diagnosis of the mutations identified in probands was offered to first-degree relatives (parents, siblings, and offspring) regardless of their clinical status. Results Molecular Analysis A mutation of HNF-1 was found in 8 of the 20 unrelated patients. Among 19 of 35 first-degree relatives from 6 unrelated families tested, 5 of 8 offspring had inherited a mutation. None of the 8 mutations have been reported to date. All are located in the DNA-binding domain (20). Five are point mutations resulting in amino acid substitutions (also called missense mutations) that affect residues conserved in HNF-1 human, pig, mouse, rat, xenopus, and salmon sequences. Two other mutations are nonsense mutations resulting in a truncated protein lacking the 3-part of the DNA-binding domain and the C-terminal transactivation domain. The last mutation is localized in the splice donor site of intron 2 at the highly conserved +1 position. Another base change (GA) at the same position was described in a Japanese family with MODY5 (8). No nucleotide variant was detected in 212 control chromosomes of unrelated nondiabetic white participants and in 170 chromosomes of patients with classic type 2 diabetes. In 4 families (families 1, 5, 6, and 8), cosegregation of a HNF-1 mutation and MODY5 phenotype was consistent with dominant inheritance because 5 affected offspring inherited the mutation detected in the proband. A de novo mutation was demonstrated in 2 probands (patient II-1, family 6, and patient II-1, family 7). In each case, the probands parents were not carriers of the mutation. Parental relationships were confirmed by using microsatellite markers (data not shown). Two relatives in family 3 (patients I-2 and II-1) and 2 relatives in family 6 (patients I-1 and I-2) had diabetes mellitus but did not exhibit the corresponding mutation of HNF-1. Clinical Phenotype Diabetes was present in all probands and in 2 offspring (patient III-1, family 1, and patient II-1, family 8) with a mutation. Five patients presented with clinical symptoms, including severe metabolic decompensation in 2 patients, at age 1 year (patient II-1, family 8) and 13 (patient II-1, family 6) years, respectively. In the 5 other patients, diabetes was found by routine plasma glucose measurement. Clinical characteristics were consistent with a defect of insulin secretion: All patients were lean at diagnosis, ketosis was observed in 2 patients, and progression of the disease was observed in 3 patients who ultimately required insulin therapy. Endogenous insulin response to intravenous glucagon, assessed in 7 of the 8 probands, disclosed heterogeneous degrees of impairment, but residual insulin secretion was detectable in all probands. In patient II-1, family 6, endogeneous insulin secretion was measurable 22 years after diabetes was revealed by severe ketoacidosis. No patient had diabetic retinopathy or neuropathy. Pancreas atrophy was found in 5 of the 6 patients assessed by abdominal computed tomography (Table 1 and Figure). No pancreas calcification or cyst was noticed. No patient exhibited symptoms of overt pancreatic exocrine deficiency. However, of the 7 probands tested, 6 had a subclinical defect of pancreas exocrine function (Table 1 and Figure). Table 1. Characteristics of Mutations, Diabetes, Pancreas Exocrine Function, and Liver Tests in 8 Probands with Hepatocyte Nuclear Factor-1 Mutations Figure. Pancreas and kidney abnormalities in patients with hepatocyte nuclear factor-1 ( HNF-1 ) mutation. A B C. A arrow arrowheads B C. arrowheads arrows D. E F. HNF-1 E. F. arrow * Renal involvement was found in all probands (Table 2) and 4 offspring. In the probands, age at recognition of kidney disease ranged from 18 to 41 years. All exhibited structural kidney abnormalities, including decreased kidney size, ranging from 85 to 105 mm in height with global cortical loss, and a cystic pattern (Figure). Pelvicaliceal abnormalities were observed in 6 of the 7 patients who were tested and consisted of clubbing or tiny diverticulae of the calices or mild pelvic dilatation without obstructive uropathy (Figure). All probands also had mild to moderate renal failure with creatinine clearance ranging from 0.48 to 1.28 mL/s (29 to 77 mL/min). On follow-up, the mean annual decrease of creatinine clearance ranged from 0 to 0.03 mL/s (0 to 2 mL/min). It averaged 0.02 mL/s per year (1.1 mL/min per year) in the 4 patients who were followed for 14 to 16 years (Table 2). Since the clinical, biological, and radiologic characteristics of renal disease made the diagnosis of diabetic glomerulopathy very unlikely, a kidney biopsy was performed in 6 probands. No proband exhibited diabetic glomerulosclerosis. Interstitial fibrosis was observed in all biopsy specimens. Enlarged glomeruli were observed in 4 cases, associated with glom

Incompletely penetrant PKD1 alleles suggest a role for gene dosage in cyst initiation in polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) caused by mutations in PKD1 is significantly more severe than PKD2. Typically, ADPKD presents in adulthood but is rarely diagnosed in utero with enlarged, echogenic kidneys. Somatic mutations are thought crucial for cyst development, but gene dosage is also important since animal models with hypomorphic alleles develop cysts, but are viable as homozygotes. We screened for mutations in PKD1 and PKD2 in two consanguineous families and found PKD1 missense variants predicted to be pathogenic. In one family, two siblings homozygous for R3277C developed end stage renal disease at ages 75 and 62 years, while six heterozygotes had few cysts. In the other family, the father and two children with moderate to severe disease were homozygous for N3188S. In both families homozygous disease was associated with small cysts of relatively uniform size while marked cyst heterogeneity is typical of ADPKD. In another family, one patient diagnosed in childhood was found to be a compound heterozygote for the PKD1 variants R3105W and R2765C. All three families had evidence of developmental defects of the collecting system. Three additional ADPKD families with in utero onset had a truncating mutation in trans with either R3277C or R2765C. These cases suggest the presence of incompletely penetrant PKD1 alleles. The alleles alone may result in mild cystic disease; two such alleles cause typical to severe disease; and, in combination with an inactivating allele, are associated with early onset disease. Our study indicates that the dosage of functional PKD1 protein may be critical for cyst initiation.

Association of mutation position in polycystic kidney disease 1 (PKD1) gene and development of a vascular phenotype

BACKGROUND Patients with autosomal dominant polycystic kidney disease (ADPKD) are at risk of developing intracranial aneurysms, and subarachnoid haemorrhage is a major cause of death and disability. Familial clustering of intracranial aneurysms suggests that genetic factors are important in the aetiology. We tested whether the germline mutation predisposes to this vascular phenotype. METHODS DNA samples from patients with ADPKD and vascular complications were screened for mutations throughout the PKD1 and PKD2 genes. Comparisons were made between the PKD1 and PKD2 populations and with a control PKD1 cohort (without the vascular phenotype). FINDINGS Mutations were characterised in 58 ADPKD families with vascular complications; 51 were PKD1 (88%) and seven PKD2 (12%). The median position of the PKD1 mutation was significantly further 59 in the vascular population than in the 87 control pedigrees (aminoacid position 2163 vs 2773, p=0.0034). Subsets of the vascular population with aneurysmal rupture, early rupture, or families with more than one vascular case had median mutation locations further 59 (aminoacid position 1811, p=0.0018; 1671, p=0.0052; and 1587, p=0.0003). INTERPRETATION Patients with PKD2, as well as those with PKD1, are at risk of intracranial aneurysm. The position of the mutation in PKD1 is predictive for development of intracranial aneurysms (59 mutations are more commonly associated with vascular disease) and is therefore of prognostic importance. Since the PKD1 phenotype is associated with mutation position, the disease is not simply due to loss of all disease allele products.

A Cluster of Mutations in the UMOD Gene Causes Familial Juvenile Hyperuricemic Nephropathy with Abnormal Expression of Uromodulin

Familial juvenile hyperuricemic nephropathy (FJHN [MIM 162000]) is an autosomal-dominant disorder characterized by abnormal tubular handling of urate and late development of chronic interstitial nephritis leading to progressive renal failure. A locus for FJHN was previously identified on chromosome 16p12 close to the MCKD2 locus, which is responsible for a variety of autosomal-dominant medullary cystic kidney disease (MCKD2). UMOD, the gene encoding the Tamm-Horsfall/uromodulin protein, maps within the FJHN/MCKD2 critical region. Mutations in UMOD were recently reported in nine families with FJHN/MCKD2 disease. A mutation in UMOD has been identified in 11 FJHN families (10 missense and one in-frame deletion)-10 of which are novel-clustering in the highly conserved exon 4. The consequences of UMOD mutations on uromodulin expression were investigated in urine samples and renal biopsies from nine patients in four families. There was a markedly increased expression of uromodulin in a cluster of tubule profiles, suggesting an accumulation of the protein in tubular cells. Consistent with this observation, urinary excretion of wild-type uromodulin was significantly decreased. The latter findings were not observed in patients with FJHN without UMOD mutations. In conclusion, this study points to a mutation clustering in exon 4 of UMOD as a major genetic defect in FJHN. Mutations in UMOD may critically affect the function of uromodulin, resulting in abnormal accumulation within tubular cells and reduced urinary excretion.

The expanding spectrum of renal diseases associated with antiphospholipid syndrome

BACKGROUND The association of thrombotic events and/or pregnancy complications with circulating antiphospholipid antibodies defines antiphospholipid syndrome (APS). In previous reports, renal involvement in APS consisted mainly of thrombotic vascular complications involving large vessels or intrarenal small-sized vessels (APS nephropathy). We report 9 cases of glomerulonephritis associated with APS. These cases are characterized by predominant pathological features distinct from vascular APS nephropathy. METHODS We reviewed consecutive renal biopsies examined in 2 French university hospitals between 1980 and 2002 and identified renal biopsies performed in patients with primary APS. RESULTS We identified 29 biopsies performed in patients with APS. Twenty biopsies showed characteristic features of APS nephropathy. In 9 cases, predominant pathological features distinct from vascular APS nephropathy were noted: membranous nephropathy (3 cases), minimal change disease/focal segmental glomerulosclerosis (3 cases), mesangial C3 nephropathy (2 cases), and pauci-immune crescentic glomerulonephritis (1 case). In 7 cases, the presentation of renal symptoms was subacute or chronic. Two patients experienced episodes of acute renal failure. At referral, median creatinine clearance was 50 mL/min (0.83 mL/s) (range, 18 to 117 mL/min [0.30 to 1.95 mL/s]). Proteinuria was noted in all cases (range, 1.5 to 15 g/d), with nephrotic syndrome in 4 cases. Lupus anticoagulant was present in all cases, and anticardiolipin antibodies, in 8 cases. Anti-DNA antibodies repeatedly were negative in all cases. Treatment consisted of antihypertensive therapy (6 cases), anticoagulant drugs (5 cases), steroids (4 cases), and antiplatelet drugs (3 cases). At last follow-up, renal function remained stable in 7 patients. Of 2 patients presenting with acute renal failure, 1 patient recovered normal renal function, whereas the other patient progressed to end-stage renal failure. CONCLUSION The cases reported here represent a new aspect of the expanding spectrum of renal diseases encountered in association with APS.

The Spectrum of Systemic Involvement in Adults Presenting with Renal Lesion and Mitochondrial tRNA(Leu) Gene Mutation

The A3243G mutation of the mitochondrial tRNA(Leu) gene has been recently reported in rare patients with focal and segmental glomerulosclerosis (FSGS). However, the full spectrum of systemic and kidney manifestations in adults presenting with this mutation remains poorly defined. Assessment of renal and nonrenal manifestations was performed in nine patients with A3243G mutation and prominent kidney disease diagnosed in adulthood. At first renal evaluation, median age was 35 years. Renal lesions consisted of FSGS (n = 2), tubulointerstitial nephropathy (n = 3), or bilateral enlarged cystic kidneys (n = 1). All but one patient exhibited extrarenal manifestations: deafness (8 of 9) requiring hearing aid in half the cases, diabetes mellitus (3 of 9), neuromuscular involvement (2 of 9), hypertrophic cardiomyopathy (1 of 9), and macular dystrophy (1 of 9). After a median follow-up of 5 yr, five patients progressed to end-stage renal disease between the ages of 15 and 51 years, four being successfully transplanted. Similarly, extrarenal manifestations progressed since all patients had deafness and diabetes (including three posttransplants), while half had neuromuscular, cardiac, or retinal involvement. In the adult patients with A3243G mutation and renal involvement, preexisting deafness is almost consistently found. While FSGS remains the most typical lesion, tubulointerstitial nephropathy or bilateral, enlarged cystic kidneys may also be encountered. In most cases, diabetes mellitus, macular dystrophy, hypertrophic cardiomyopathy, or neuromuscular features occur later in the course of the disease. The severity of the clinical course is heterogeneous, with end-stage renal failure being reached between the second and sixth decades. Renal transplantation may be offered to these patients, despite a high incidence of steroid-induced diabetes mellitus.

Diagnosis, management, and prognosis of HNF1B nephropathy in adulthood

Mutations in HNF1B are responsible for a dominantly inherited disease with renal and nonrenal consequences, including maturity-onset diabetes of the young (MODY) type 5. While HNF1B nephropathy is typically responsible for bilateral renal cystic hypodysplasia in childhood, the adult phenotype is poorly described. To help define this we evaluated the clinical presentation, imaging findings, genetic changes, and disease progression in 27 adults from 20 families with HNF1B nephropathy. Whole-gene deletion was found in 11 families, point mutations in 9, and de novo mutations in half of the kindred tested. Renal involvement was extremely heterogeneous, with a tubulointerstitial profile at presentation and slowly progressive renal decline throughout adulthood as hallmarks of the disease. In 24 patients tested, there were cysts (≤5 per kidney) in 15, a solitary kidney in 5, hypokalemia in 11, and hypomagnesemia in 10 of 16 tested, all as characteristics pointing to HNF1B disease. Two patients presented with renal Fanconi syndrome and, overall, 4 progressed to end-stage renal failure. Extrarenal phenotypes consisted of diabetes mellitus in 13 of the 27 patients, including 11 with MODY, abnormal liver tests in 8 of 21, diverse genital tract abnormalities in 5 of 13 females, and infertility in 2 of 14 males. Thus, our findings provide data that are useful for recognition and diagnosis of HNF1B disease in adulthood and might help in renal management and genetic counseling.

Genetic heterogeneity in hypokalemic periodic paralysis (hypoPP)

Hypokalemic periodic paralysis (hypoPP) is an autosomal dominant disorder belonging to a group of muscle diseases known to involve an abnormal function of ion channels. The latter includes hypokalemic and hyperkalemic periodic paralyses, and non-dystrophic myotonias. We recently showed genetic linkage of hypoPP to loci on chromosome 1q31-32, co-localized with the DHP-sensitive calcium channel CACNL1A3. We propose to term this locus hypoPP-1. Using extended haplotypes with new markers located on chromosome 1q31-32, we now report the detailed mapping of hypoPP-1 within a 7 cM interval. Two recombinants between hypoPP-1 and the flanking markers D1S413 and D1S510 should help to reduce further the hypoPP-1 interval. We used this new information to demonstrate that a large family of French origin displaying hypoPP is not genetically linked to hypoPP-1. We excluded genetic linkage over the entire hypoPP-1 interval showing for the first time genetic heterogeneity in hypoPP.

Specific Macrophage Subtypes Influence the Progression of Rhabdomyolysis-Induced Kidney Injury

Rhabdomyolysis can be life threatening if complicated by AKI. Macrophage infiltration has been observed in rat kidneys after glycerol-induced rhabdomyolysis, but the role of macrophages in rhabdomyolysis-induced AKI remains unknown. Here, in a patient diagnosed with rhabdomyolysis, we detected substantial macrophage infiltration in the kidney. In a mouse model of rhabdomyolysis-induced AKI, diverse renal macrophage phenotypes were observed depending on the stage of the disease. Two days after rhabdomyolysis, F4/80(low)CD11b(high)Ly6b(high)CD206(low) kidney macrophages were dominant, whereas by day 8, F4/80(high)CD11b(+)Ly6b(low)CD206(high) cells became the most abundant. Single-cell gene expression analyses of FACS-sorted macrophages revealed that these subpopulations were heterogeneous and that individual cells simultaneously expressed both M1 and M2 markers. Liposomal clodronate-mediated macrophage depletion significantly reduced the early infiltration of F4/80(low)CD11b(high)Ly6b(high)CD206(low) macrophages. Furthermore, transcriptionally regulated targets potentially involved in disease progression, including fibronectin, collagen III, and chemoattractants that were identified via single-cell analysis, were verified as macrophage-dependent in situ. In vitro, myoglobin treatment induced proximal tubular cells to secrete chemoattractants and macrophages to express proinflammatory markers. At day 30, liposomal clodronate-mediated macrophage depletion reduced fibrosis and improved both kidney repair and mouse survival. Seven months after rhabdomyolysis, histologic lesions were still present but were substantially reduced with prior depletion of macrophages. These results suggest an important role for macrophages in rhabdomyolysis-induced AKI progression and advocate the utility of long-term follow-up for patients with this disease.

Oxalate Nephropathy Associated with Chronic Pancreatitis

BACKGROUND AND OBJECTIVES Enteric overabsorption of oxalate may lead to hyperoxaluria and subsequent acute oxalate nephritis (AON). AON related to chronic pancreatitis is a rare and poorly described condition precluding early recognition and treatment. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We collected the clinical characteristics, treatment, and renal outcome of 12 patients with chronic pancreatitis-associated AON followed in four French renal units. RESULTS Before AON, mild to moderate chronic kidney disease was present in all patients, diabetes mellitus in eight (insulin [n = 6]; oral antidiabetic drugs [n = 2]), and known chronic pancreatitis in only eight. At presentation, pancreas imaging showed gland atrophy/heterogeneity, Wirsung duct dilation, calcification, or pseudocyst. Renal findings consisted of rapidly progressive renal failure with tubulointerstitial profile. Acute modification of glomerular filtration preceded the AON (i.e., diarrhea and diuretics). Increase in urinary oxalate excretion was found in all tested patients and hypocalcemia in nine (<1.5 mmol/L in four patients). Renal biopsy showed diffuse crystal deposits, highly suggestive of oxalate crystals, with tubular necrosis and interstitial inflammatory cell infiltrates. Treatment consisted of pancreatic enzyme supplementation, oral calcium intake, and an oxalate-free diet in all patients and renal replacement therapy in five patients. After a median follow-up of 7 months, three of 12 patients reached end-stage renal disease. CONCLUSION AON is an under-recognized severe crystal-induced renal disease with features of tubulointerstitial nephritis that may occur in patients with a long history of chronic pancreatitis or reveal the pancreatic disease. Extrinsic triggering factors should be prevented.