A functional variant in NEPH3 gene confers high risk of renal failure in primary hematuric glomerulopathies. Evidence for predisposition to microalbuminuria in the general population.

BACKGROUND: Recent data emphasize that thin basement membrane nephropathy (TBMN) should not be viewed as a form of benign familial hematuria since chronic renal failure (CRF) and even end-stage renal disease (ESRD), is a possible development for a subset of patients on long-term follow-up, through the onset of focal and segmental glomerulosclerosis (FSGS). We hypothesize that genetic modifiers may explain this variability of symptoms. METHODS: We looked in silico for potentially deleterious functional SNPs, using very strict criteria, in all the genes significantly expressed in the slit diaphragm (SD). Two variants were genotyped in a cohort of well-studied adult TBMN patients from 19 Greek-Cypriot families, with a homogeneous genetic background. Patients were categorized as "Severe" or "Mild", based on the presence or not of proteinuria, CRF and ESRD. A larger pooled cohort (HEMATURIA) of 524 patients, including IgA nephropathy patients, was used for verification. Additionally, three large general population cohorts [Framingham Heart Study (FHS), KORAF4 and SAPHIR] were used to investigate if the NEPH3-V353M variant has any renal effect in the general population. RESULTS AND CONCLUSIONS: Genotyping for two high-scored variants in 103 TBMN adult patients with founder mutations who were classified as mildly or severely affected, pointed to an association with variant NEPH3-V353M (filtrin). This promising result prompted testing in the larger pooled cohort (HEMATURIA), indicating an association of the 353M variant with disease severity under the dominant model (p = 3.0x10-3, OR = 6.64 adjusting for gender/age; allelic association: p = 4.2x10-3 adjusting for patients' kinships). Subsequently, genotyping 6,531 subjects of the Framingham Heart Study (FHS) revealed an association of the homozygous 353M/M genotype with microalbuminuria (p = 1.0x10-3). Two further general population cohorts, KORAF4 and SAPHIR confirmed the association, and a meta-analysis of all three cohorts (11,258 individuals) was highly significant (p = 1.3x10-5, OR = 7.46). Functional studies showed that Neph3 homodimerization and Neph3-Nephrin heterodimerization are disturbed by variant 353M. Additionally, 353M was associated with differential activation of the unfolded protein response pathway, when overexpressed in stressed cultured undifferentiated podocyte cells, thus attesting to its functional significance. Genetics and functional studies support a "rare variant-strong effect" role for NEPH3-V353M, by exerting a negative modifier effect on primary glomerular hematuria. Additionally, genetics studies provide evidence for a role in predisposing homozygous subjects of the general population to micro-albuminuria

Real world application of ATA guidelines in over 600 aspirated thyroid nodules:is it time to change the size cut-offs for FNA?

BACKGROUND: The 2015 American Thyroid Association (ATA) Guidelines recommend the following size cut-offs based on sonographic appearances for subjecting nodules to fine-needle aspiration (FNA) biopsy: low risk: 15 mm and intermediate risk and high risk: 10 mm. OBJECTIVE: We conducted a ‘real-world’ study evaluating the diagnostic performance of the ATA cut-offs against increased thresholds, in the interest of safely limiting FNAs. METHODS: We performed a retrospective analysis of prospectively collected data on 604 nodules which were sonographically risk-stratified as per the ATA Guidelines and subsequently subjected to ultrasound-guided FNA. Nodules were cytologically stratified into ‘benign’ (Bethesda class 2) and ‘non-benign’ (Bethesda classes 3–6). We obtained the negative predictive value (NPV), accuracy, FNAs that could be spared, missed ‘non-benign’ cytologies and missed carcinomas on histology, according to the ATA cut-offs compared to higher cut-offs. RESULTS: In low-risk nodules, the high performance of NPV (≈91%) is unaffected by increasing the cut-off to 25 mm, and accuracy improves by 39.4%; 46.8% of FNAs could be spared at the expense of few missed B3–B6 cytologies (7.9%) and no missed carcinomas. In intermediate-risk nodules, a 15 mm cut-off increases the NPV by 11.3% and accuracy by 40.7%. The spared FNAs approach 50%, while B3–B6 cytologies are minimal, with no missed carcinomas. In high-risk nodules, low NPV (<35%) and accuracy (<46%) were obtained regardless of cut-off. Moreover, the spared FNAs achieved at higher cut-offs involved numerous missed ‘non-benign’ cytologies and carcinomas. CONCLUSION: It would be clinically safe to increase the ATA cut-offs for FNA in low-risk nodules to 25 mm and in intermediate-risk nodules to 15 mm

Clinico-pathological correlations in 127 patients in 11 large pedigrees, segregating one of three heterozygous mutations in the COL4A3/ COL4A4 genes associated with familial haematuria and significant late progression to proteinuria and chronic kidney disease from focal segmental glomerulosclerosis

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Heterozygous mutations in the &lt;i&gt;COL4A3/ COL4A4&lt;/i&gt; genes are currently thought to be responsible for familial benign microscopic haematuria and maintenance of normal long-term kidney function.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods.&lt;/strong&gt; We report on 11 large Cypriot pedigrees with three such mutations. A total of 236 at-risk family members were genetically studied, and 127 (53.8%) carried a heterozygous mutation. Clinico-pathological correlations were available in all of these patients. Renal biopsies in 21 of these patients all showed various stages of focal, segmental glomerulosclerosis (FSGS). Thirteen of these biopsies were also studied with EM and showed thinning of the glomerular basement membrane.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results.&lt;/strong&gt; Mutation G1334E (&lt;i&gt;COL4A3&lt;/i&gt;) was found in six pedigrees, mutation G871C (&lt;i&gt;COL4A3&lt;/i&gt;) in four and mutation 3854delG (&lt;i&gt;COL4A4&lt;/i&gt;) in one pedigree. Clinical and laboratory correlations in all 127 mutation carriers (MC) showed that microscopic haematuria was the only urinary finding in patients under age 30. The prevalence of 'haematuria alone' fell to 66% between 31 and 50 years, to 30% between 51 and 70 and to 23% over age 71. Proteinuria with CRF developed on top of haematuria in 8% of all MC between 31 and 50 years, to 25% between 51 and 70 years and to 50% over 71 years. Altogether 18 of these 127 MC (14%) developed ESRD at a mean age of 60 years. Two members with different mutations married, and two of their children inherited both mutations and developed adolescent, autosomal recessive Alport syndrome (ATS), confirming that these mutations are pathogenic.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions.&lt;/strong&gt; Our data confirm for the first time a definite association of heterozygous &lt;i&gt;COL4A3/COL4A4&lt;/i&gt; mutations with familial microscopic haematuria, thin basement membrane nephropathy and the late development of familial proteinuria, CRF, and ESRD, due to FSGS, indicating that the term 'benign familial haematuria' is a misnomer, at least in this cohort. A strong hypothesis for a causal relationship between these mutations and FSGS is also made. Benign familial haematuria may not be so benign as commonly thought.&lt;/p&gt

Familial C3 Glomerulopathy Associated with CFHR5 Mutations: Clinical Characteristics of 91 Patients in 16 Pedigrees

Background and objectives Complement factor H and related proteins (CFHR) are key regulators of the alternative complement pathway, where loss of function mutations lead to a glomerulopathy with isolated mesangial C3 deposits without immunoglobulins. Gale et al. (12) reported on 26 patients with the first familial, hematuric glomerulopathy caused by a founder mutation in the CFHR5 gene in patients of Cypriot descent living in the United Kingdom. CFHR5 nephropathy is clinically characterized by continuous microscopic hematuria whereas some patients present with additional episodes of synpharyngitic macrohematuria, associated with infection and pyrexia. A subgroup of patients, particularly men, develop additional proteinuria, hypertension, and chronic renal disease or ESRD.Design, setting, participants, & measurements We herewith expand significantly on the study by Gale et al., reporting on histologic, molecular, and clinical findings in 91 patients from 16 families with the same founder mutation.Results Eighty-two patients (90%) exhibited microscopic hematuria; 51(62%), exhibited only microscopic hematuria, whereas the remaining 31 additionally had proteinuria (38%); 28 proteinuric patients developed chronic renal failure (CRF). Among carriers of CFHR5 mutation aged >50 years, 80% of the men and 21% of the women developed CRF; 18 developed ESRD (14 men [78%], 4 women [22%]).Conclusions The diagnosis of CFHR5-related, isolated C3 glomerulopathy was established in 2009 using newly described mutation analysis after decades of follow-up with unclear diagnoses, occasionally confused with IgA nephropathy. This larger patient cohort establishes the clinical course, significant variable expressivity, and marked gender difference regarding the development of CRF and ESRD. Clin J Am Soc Nephrol 6: 1436-1446, 2011. doi: 10.2215/CJN.0954101

Genotype associations for the three <i>MYH9</i> variants genotyped in this study.

<p>P-values were calculated by Pearson Chi-Square test. The whole CFHR5 cohort (B) was genotyped only for <i>MYH9</i> rs11089788, the only SNP that gave p-value close to 0.1 for the male CFHR5 patients (B1).</p>*<p>P-values calculated by Fisher's Exact Test (2-sided) due to existence of genotypes values less than 10.</p>**<p>Odds ratio (OR) cannot be estimated due to zero genotypic values in the “Severe” category.</p

Description of cohorts and patients under study.

<p>Please note that cohort B1 is the male only patients with CFHR5 nephropathy.</p><p>MH: Microscopic Hematuria, ESKD: End Stage Kidney Disease, XLAS: X-linked Alport syndrome.</p>1<p>“Mild” patients born before 01/1963. Gender difference (Mild vs Severe) is not significant (p = 0.141).</p>2<p>“Mild” patients born before 01/1975. Gender difference (Mild vs Severe) is significant (p = 0.001).</p>3<p>“Severe” patients: ESKD≤40 yo.</p>4<p>“Mild” patients born before 01/1979. Gender difference (Mild vs Severe) is significant (p = 0.001).</p

Genotype distribution of the studied <i>MYH9</i> variants, by cohort and by severity.

<p>Genotype distribution of the studied <i>MYH9</i> variants, by cohort and by severity.</p

<i>MYH9</i> rs11089788 statistical analysis for a replicate cohort (D) and for the sum of cohorts B and D, that gave statistical significance.

<p>Patients in cohort D belong to families that segregate microscopic hematuria but no known mutation has been found in any of the genes <i>COL4A3</i>, <i>COL4A4</i>, or <i>CFHR5</i>, so far.</p