Biomedical subjects

Gerald B Appel

Publications and source records attributed to Gerald B Appel.

10 recordsLinked to original sources

PubMed2026

Precision Diagnosis in APOL1 Kidney Disease With the p.N264K M1 Protective Variant.

IMPORTANCE: The APOL1 M1 (p.N264K) variant protects against G2-associated APOL1 focal segmental glomerulosclerosis (FSGS) and chronic kidney disease (CKD). However, the utility of knowing an individual's M1 status in guiding kidney disease diagnosis and other clinical scenarios remains underexplored. OBJECTIVE: To test 2 hypotheses: (1) in patients with APOL1 high-risk (HR) genotype kidney disease with at least 1 G2 allele, M1 can distinguish APOL1 CKD from non-APOL1 CKD; (2) in people with APOL1 low-risk (LR) genotypes, M1 is independently associated with protection against FSGS and CKD. DESIGN, SETTING, AND PARTICIPANTS: Retrospective case-control study using data from 2 tertiary care hospitals (Columbia University Irving Medical Center and Mass General Brigham Biobank) and population-based data (the UK Biobank [UKB], Electronic Medical Records and Genomics [eMERGE-III], and All of Us [AoU]). Participants were individuals with a diagnosis of FSGS or steroid-resistant nephrotic syndrome (SRNS), individuals with CKD, and controls. EXPOSURES: Exposures included the M1 variant (p.N264K) obtained from exome or genome sequencing data, sex, and genetic ancestry. MAIN OUTCOME AND MEASURE: The main outcome was the presence or absence of kidney disease, defined as FSGS or non-FSGS CKD, compared with non-kidney disease controls. Association between the M1 variant and disease status was assessed using odds ratios (ORs). RESULTS: A total of 107 696 individuals (54 994 [51.1%] female; 8779 [8.2%] with African ancestry, 78 475 [72.9%] with European ancestry, and 16 129 [15.0%] with multiethnic ancestry), including 3460 with FSGS or SRNS, 24 382 with non-FSGS CKD kidney disease, and 79 854 controls were enrolled in the discovery cohort. In the APOL1-HR group (1413 participants), M1 was significantly inversely associated with FSGS or SRNS cases compared with controls without kidney disease (OR, 0.20; 95% CI, 0.04-0.63; P = 3.69 × 10-3). Among individuals with CKD with APOL1-HR genotypes, M1 was 4 times more frequent in those whose CKD was not due to FSGS or SRNS. Importantly, electronic health record and biopsy review identified an alternative, non-APOL1 cause for CKD in nearly all APOL1-HR-M1 cases. There was no association between individuals with APOL1-LR genotypes with M1 and protection against CKD or FSGS. CONCLUSIONS AND RELEVANCE: In this case-control study of 107 696 individuals, presence of an APOL1-HR genotype M1 was significantly associated with protection against kidney disease, suggesting that it may have a role as a genetic modifier. Patients with CKD with an APOL1-HR genotype and M1 should be evaluated for an alternative and potentially treatable cause of their CKD.

Humans↗

PubMed2003

Hyperlipidemia and thrombotic complications in patients with membranous nephropathy.

Membranous nephropathy (MN), the most common cause of adult-onset nephrotic syndrome (NS) in Caucasians, is associated commonly with the secondary complications of hyperlipidemia and hypercoagulability. These may increase the risk for cardiovascular disease, alter the rate of progression of renal disease, and raise the risk for thromboembolic events. The treatment of these secondary effects remains controversial. Although no clear practice guidelines are available to assist the clinician in deciding how and when to start disease-modifying therapies, the literature provides enough information to make reasonable decisions in most clinical scenarios. Prospective trials in the future will provide definitive information on how to best treat these abnormalities.

Anticoagulants↗

PubMed2003

Fibrillary and immunotactoid glomerulonephritis: Distinct entities with different clinical and pathologic features.

BACKGROUND: Controversy surrounds the relatedness of fibrillary glomerulonephritis (FGN) and immunotactoid glomerulonephritis (IT). METHODS: To better define their clinicopathologic features and outcome, we report the largest single center series of 67 cases biopsied from 1980 to 2001, including 61 FGN and 6 IT. FGN was defined by glomerular immune deposition of Congo red-negative randomly oriented fibrils of < 30 nm (mean, 20.1 +/- 0.4 nm). IT was defined by glomerular deposition of hollow, stacked microtubules of > or = 30 nm (mean, 38.2 +/- 5.7 nm). RESULTS: FGN comprised 0.6% of total native kidney biopsies and IT was tenfold more rare (0.06%). Deposits in FGN were immunoglobulin G (IgG) dominant and polyclonal in 96%. IgG subtype analysis in 19 FGN cases showed monotypic deposits in four (two IgG1 and two IgG4) and oligotypic deposits in 15 (all combined IgG1 and IgG4). In IT, deposits were IgG dominant in 83% and monoclonal in 67% (three IgG1 kappa and one IgG1 lambda). FGN patients were a mean age of 57 years, 92% were Caucasian, and 39% were male. At biopsy, FGN patients had the following clinical characteristics (mean, range): creatinine 3.1 mg/dL (0.5 to 14), proteinuria 6.5 g/day (0.8 to 25), 60% microhematuria, and 59% hypertension. Histologic patterns of FGN were diverse, including diffuse proliferative glomerulonephritis (DPGN) (nine cases), membranoproliferative glomerulonephritis (MPGN) (27 cases), mesangial proliferative/sclerosing (MES) (13), membranous glomerulonephritis (MGN) (four), and diffuse sclerosing (DS) (eight). The more proliferative (MPGN and DPGN) and sclerosing (DS) forms presented with a higher creatinine and greater proteinuria compared to MES and MGN. Median time to end-stage renal disease (ESRD) was 24.4 months for FGN and mean time to ESRD varied by histologic subtype: DS 7 months, DPGN 20 months, MPGN 44 months, compared to MES 80 months and MGN 87 months. There was no statistically significant effect of immunosuppressive therapy (given to 36% of FGN patients). By Cox regression (hazard ratio, confidence interval, P value), independent predictors of progression to ESRD were creatinine at biopsy [2.05 (1.55 to 2.72) P < 0.001] and severity of interstitial fibrosis [2.01 (1.05 to 3.85) P = 0.034]. Although IT had similar presentation, histologic patterns, and outcome compared to FGN, it had a greater association with monoclonal gammopathy (P = 0.014), underlying lymphoproliferative disease (P = 0.020), and hypocomplementemia (P = 0.032). CONCLUSION: FGN is an idiopathic condition characterized by polyclonal immune deposits with restricted gamma isotypes. Most patients present with significant renal insufficiency and have a poor outcome despite immunosuppressive therapy, and outcome correlates with histologic subtype. By contrast, IT often contains monoclonal IgG deposits and has a significant association with underlying dysproteinemia and hypocomplementemia. Differentiation of FGN from the much more rare entity IT appears justified on immunopathologic, ultrastructural, and clinical grounds.

Adult↗

PubMed2003

Collapsing glomerulopathy.

Collapsing glomerulopathy is a morphologic variant of focal segmental glomerulosclerosis (FSGS) characterized by segmental and global collapse of the glomerular capillaries, marked hypertrophy and hyperplasia of podocytes, and severe tubulointerstitial disease. The cause of this disorder is unknown, but nearly identical pathologic findings are present in idiopathic collapsing glomerulopathy and human immunodeficiency virus (HIV)-associated nephropathy, and collapsing glomerulopathy has been associated with parvovirus B19 infection and treatment with pamidronate. The pathogenesis of collapsing glomerulopathy involves visceral epithelial cell injury leading to cell cycle dysregulation and a proliferative phenotype. Clinically, collapsing glomerulopathy is characterized by black racial predominance, a high incidence of nephrotic syndrome, and rapidly progressive renal failure. Collapsing glomerulopathy also may recur after renal transplantation or present de novo, often leading to loss of the allograft. The optimal treatment for collapsing glomerulopathy is unknown. Treatments may include steroids or cyclosporine in addition to aggressive blood pressure control, angiotensin converting enzyme inhibitors and/or angiotensin II receptor blockers, and lipid lowering agents. The role of other immunosuppressive agents such as mycophenolate mofetil in the treatment of collapsing FSGS remains to be defined. Prospective clinical trials are needed to define optimal therapy of this aggressive form of FSGS.

Capillaries↗

PubMed2003

Prognosis in proliferative lupus nephritis: the role of socio-economic status and race/ethnicity.

BACKGROUND: Studies of proliferative lupus nephritis (PLN) suggest that African-Americans have a poorer prognosis than Whites. However, no study has simultaneously examined socio-economic status. We studied rates of progression of PLN among a tri-ethnic population with respect to socio-economic status and race/ethnicity. METHODS: A retrospective cohort study was carried out using individual and census-based neighbourhood data. Consecutive patients in urban tertiary care centres with biopsy-proven PLN were studied. The main outcome was time to doubling of serum creatinine. RESULTS: Among 128 patients with PLN, the percentage of patients who did not double their serum creatinine at 5 years was 67.0% (+/-4.8%) and at 10 years was 58.9% (+/-5.7%). In bivariate analyses, residence in a poor neighbourhood was positively associated with progression (P = 0.03), as was African-American and Hispanic race/ethnicity (P = 0.01). Residence in a poor neighbourhood remained associated with progression of disease after adjustment for age, sex, creatinine, hypertension, cyclophosphamide treatment and race/ethnicity [relative risk (RR) 3.5, 95% confidence interval (CI) 1.2-11, P = 0.03]. After adjustment for poverty and insurance, the RR for African-American race/ethnicity was reduced from 3.5 to 2.7 and was not statistically associated with progression of disease in the full model (P = 0.10). A similar reduction in RR from 5.5 to 3.6 was seen for Hispanic race/ethnicity, but this retained statistical significance (P = 0.03). CONCLUSIONS: Poverty is an important risk factor for progression of PLN, independent of race/ethnicity. Hispanics have an elevated risk similar to or greater than African-Americans. Given these findings, some of the poorer prognosis of African-American patients with PLN may result from socio-economic rather than biological or genetic factors.

Adolescent↗

PubMed2003

Analysis of metabolic parameters as predictors of risk in the RENAAL study.

OBJECTIVE: Metabolic factors such as glycemic control, hyperlipidemia, and hyperkalemia are important considerations in the treatment of patients with type 2 diabetes and nephropathy. In the RENAAL (Reduction of End Points in Type 2 Diabetes With the Angiotensin II Antagonist Losartan) study, losartan reduced renal outcomes in the patient population. This post hoc analysis of the RENAAL study reports the effects of losartan on selected metabolic parameters and assesses the relationship between baseline values of metabolic parameters and the primary composite end point or end-stage renal disease (ESRD). RESEARCH DESIGN AND METHODS: Glycemic control (HbA(1c)) and serum lipid, uric acid, and potassium levels were compared between the losartan and placebo groups over time, and baseline levels were correlated with the risk of reaching the primary composite end point (doubling of serum creatinine, ESRD, or death) or ESRD alone. RESULTS: Losartan did not adversely affect glycemic control or serum lipid levels. Losartan-treated patients had lower total (227.4 vs. 195.4 mg/dl) and LDL (142.2 vs. 111.7 mg/dl) cholesterol. Losartan was associated with a mean increase of up to 0.3 mEq/l in serum potassium levels; however, the rate of hyperkalemia-related discontinuation was similar between the placebo and losartan groups. Univariate analysis revealed that baseline total and LDL cholesterol and triglyceride levels were associated with increased risk of developing the primary composite end point. Similarly, total and LDL cholesterol were also associated with increased risk of developing ESRD. CONCLUSIONS: Overall, losartan was well tolerated by patients with type 2 diabetes and nephropathy and was associated with a favorable effect on the metabolic profile of this population.

Cholesterol↗

PubMed2002

Fludarabine treatment of cryoglobulinemic glomerulonephritis.

Three patients (one hepatitis C positive) presented with renal insufficiency and nephrotic-range proteinuria resulting from mixed cryoglobulinemia and glomerulonephritis. All three patients received two to four cycles of intravenous fludarabine (each cycle consisted of 25 to 50 mg/d for 4 to 5 days). All patients responded to therapy with a decrease in proteinuria, increase in serum albumin, and decrease in serum creatinine. This response was evident by 2 months and persisted for 2 to 5 years. In two patients, this response was accompanied by disappearance of cryoglobulins, at least transiently. One patient developed tuberculosis with neutropenia. Transient blindness and neutropenia were seen in another patient. These results suggest that fludarabine may be a useful treatment in cryoglobulinemia with glomerulonephritis, although its use may be accompanied by side effects.

Adult↗

PubMed2002

NPHS2 mutations in late-onset focal segmental glomerulosclerosis: R229Q is a common disease-associated allele.

Mutations in NPHS2, encoding podocin, have been identified in childhood onset focal and segmental glomerulosclerosis (FSGS). The role of NPHS2 in adult disease is less well defined. We studied 30 families with FSGS and apparent autosomal recessive inheritance and 91 individuals with primary FSGS. We screened family members for NPHS2 mutations. NPHS2 mutations appeared to be responsible for disease in nine of these families. In six families, the affected individuals were compound heterozygotes for a nonconservative R229Q amino acid substitution. This R229Q variant has an allele frequency of 3.6% in a control population. In these families, R229Q was the only mutation identified on one of the two disease-associated NPHS2 alleles. We used in vitro-translated podocin and purified nephrin to investigate the effect of R229Q on their interaction and found decreased nephrin binding to the R229Q podocin. These data suggest that this common polymorphism contributes to the development of FSGS. Chromosomes bearing the R229Q mutation share a common haplotype defining an approximately 0.2-Mb region. R229Q appears to enhance susceptibility to FSGS in association with a second mutant NPHS2 allele. Identification of R229Q mutations may be of clinical importance, as NPHS2-associated disease appears to define a subgroup of FSGS patients unresponsive to corticosteroids.

Adolescent↗

PubMed2001

Collapsing focal segmental glomerulosclerosis following treatment with high-dose pamidronate.

Collapsing focal segmental glomerulosclerosis (FSGS) is a distinct clinicopathologic entity seen most commonly in young African American patients who present with renal insufficiency and nephrotic syndrome. The only epidemiologic factor previously linked to collapsing FSGS is HIV infection. Here clinicopathologic findings are reported for a distinctive population of seven patients, who were older, Caucasian, and HIV negative and developed collapsing FSGS during active treatment of malignancy (multiple myeloma in six patients and metastatic breast carcinoma in one). Although oncologic treatment regimens included vincristine for four patients, doxorubicin for five patients, cisplatin for two patients, and total-body irradiation for one patient, the only agent common to all patients was pamidronate (Aredia). All patients had normal renal function before the administration of pamidronate. Patients began therapy with pamidronate at or below the recommended dose of 90 mg, intravenously, monthly, which was increased to 180 mg monthly in two patients and 360 mg monthly in three patients. Patients received pamidronate for 15 to 48 mo before presentation with renal insufficiency (mean serum creatinine, 3.6 mg/dl) and full nephrotic syndrome (mean 24-h urinary protein excretion, 12.4 g/d). Pamidronate, which is a member of the class of bisphosphonates, is widely used in the treatment of hypercalcemia of malignancy and osteolytic metastases. At the recommended dose of 90 mg, intravenously, monthly, renal toxicity is infrequent; however, higher doses have produced nephrotoxicity in animal models. The temporal association between pamidronate therapy and the development of renal insufficiency, the use of escalating doses that exceed recommended levels, and the distinctive pattern of glomerular and tubular injury strongly suggest a mechanism of drug-associated podocyte and tubular toxicity. These data provide the first association of collapsing FSGS with toxicity to a therapeutic agent.

Aged↗

PubMed2001

Renal monoclonal immunoglobulin deposition disease: the disease spectrum.

This study reports the clinicopathologic findings and outcome in 34 patients with renal monoclonal immunoglobulin deposition disease (MIDD), which included 23 light-chain DD (LCDD), 5 light- and heavy-chain DD (LHCDD), and 6 heavy-chain DD (HCDD). A total of 23 patients had pure MIDD, whereas 11 patients had LCDD with coexistent myeloma cast nephropathy (LCDD & MCN). Renal biopsy diagnosis preceded clinical evidence of dysproteinemia in 68% of all cases. By immunofluorescence, the composition of deposits included 11kappa/1lambda (LCDD), 3IgGkappa/2IgGlambda (LHCDD), 5gamma/1alpha (HCDD), and 10kappa/1lambda (LCDD & MCN). Patients with pure MIDD presented with mean serum creatinine of 4.2 mg/dl, nephrotic proteinuria, and hypertension. Cases of HCDD were associated with a CH1 deletion and frequently had hypocomplementemia and a positive hepatitis C virus antibody but negative hepatitis C virus PCR. LCDD & MCN is a morphologically and clinically distinct entity from pure MIDD, presenting with higher creatinine (mean, 7.8 mg/dl; P = 0.01), greater dialysis dependence (64 versus 26%; P = 0.053), subnephrotic proteinuria, and less nodular glomerulopathy (18 versus 100%; P < 0.0001). Multiple myeloma was more frequently diagnosed in LCDD & MCN than in pure MIDD (91 versus 31%; P = 0.025). Renal and patient survivals were significantly worse in patients with LCDD & MCN (mean, 4 and 22 mo, respectively), compared with patients with pure MIDD (mean, 22 and 54 mo). Chemotherapy stabilized or improved renal function in 10 of 15 patients (67%) with pure MIDD who presented with creatinine of <5.0 mg/dl, emphasizing the importance of early detection. On multivariate analysis, initial creatinine was the only predictor of renal and patient survival in pure MIDD, underscoring the prognostic significance of the renal involvement.

Aged↗