Apolipoprotein L1 gene variants in deceased organ donors are associated with renal allograft failure.

Apolipoprotein L1 gene (APOL1) nephropathy variants in African American deceased kidney donors were associated with shorter renal allograft survival in a prior single-center report. APOL1 G1 and G2 variants were genotyped in newly accrued DNA samples from African American deceased donors of kidneys recovered and/or transplanted in Alabama and North Carolina. APOL1 genotypes and allograft outcomes in subsequent transplants from 55 U.S. centers were linked, adjusting for age, sex and race/ethnicity of recipients, HLA match, cold ischemia time, panel reactive antibody levels, and donor type. For 221 transplantations from kidneys recovered in Alabama, there was a statistical trend toward shorter allograft survival in recipients of two-APOL1-nephropathy-variant kidneys (hazard ratio [HR] 2.71; p = 0.06). For all 675 kidneys transplanted from donors at both centers, APOL1 genotype (HR 2.26; p = 0.001) and African American recipient race/ethnicity (HR 1.60; p = 0.03) were associated with allograft failure. Kidneys from African American deceased donors with two APOL1 nephropathy variants reproducibly associate with higher risk for allograft failure after transplantation. These findings warrant consideration of rapidly genotyping deceased African American kidney donors for APOL1 risk variants at organ recovery and incorporation of results into allocation and informed-consent processes.

Implication of European-derived adiposity loci in African Americans.

OBJECTIVE: Recent genome-wide association studies (GWAS) have identified multiple novel loci associated with adiposity in European-derived study populations. Limited study of these loci has been reported in African Americans. Here we examined the effects of these previously identified adiposity loci in African Americans. METHODS: A total of 46 representative single-nucleotide polymorphisms (SNPs) in 19 loci that were previously reported in GWAS in Europeans (including FTO and MC4R) were genotyped in 4992 subjects from six African-American cohorts. These SNPs were tested for association with body mass index (BMI) after adjustment for age, gender, disease status and population structure in each cohort. Meta-analysis was conducted to combine the results. RESULTS: Meta-analysis of 4992 subjects revealed seven SNPs near four loci, including NEGR1, TMEM18, SH2B1 /ATP2A1 and MC4R, showing significant association at 0.005

The APOL1 gene and allograft survival after kidney transplantation.

Coding variants in the apolipoprotein L1 gene (APOL1) are strongly associated with nephropathy in African Americans (AAs). The effect of transplanting kidneys from AA donors with two APOL1 nephropathy risk variants is unknown. APOL1 risk variants were genotyped in 106 AA deceased organ donors and graft survival assessed in 136 resultant kidney transplants. Cox-proportional hazard models tested for association between time to graft failure and donor APOL1 genotypes. The mean follow-up was 26.4 ± 21.8 months. Twenty-two of 136 transplanted kidneys (16%) were from donors with two APOL1 nephropathy risk variants. Twenty-five grafts failed; eight (32%) had two APOL1 risk variants. A multivariate model accounting for donor APOL1 genotype, overall African ancestry, expanded criteria donation, recipient age and gender, HLA mismatch, CIT and PRA revealed that graft survival was significantly shorter in donor kidneys with two APOL1 risk variants (hazard ratio [HR] 3.84; p = 0.008) and higher HLA mismatch (HR 1.52; p = 0.03), but not for overall African ancestry excluding APOL1. Kidneys from AA deceased donors harboring two APOL1 risk variants failed more rapidly after renal transplantation than those with zero or one risk variants. If replicated, APOL1 genotyping could improve the donor selection process and maximize long-term renal allograft survival.

Variants in intron 13 of the ELMO1 gene are associated with diabetic nephropathy in African Americans.

Variants in the engulfment and cell motility 1 (ELMO1) gene are associated with nephropathy due to type 2 diabetes mellitus (T2DM) in a Japanese cohort. We comprehensively evaluated this gene in African American (AA) T2DM patients with end-stage renal disease (ESRD). Three hundred and nine HapMap tagging SNPs and 9 reportedly associated SNPs were genotyped in 577 AA T2DM-ESRD patients and 596 AA non-diabetic controls, plus 43 non-diabetic European American controls and 45 Yoruba Nigerian samples for admixture adjustment. Replication analyses were conducted in 558 AA with T2DM-ESRD and 564 controls without diabetes. Extension analyses included 328 AA with T2DM lacking nephropathy and 326 with non-diabetic ESRD. The original and replication analyses confirmed association with four SNPs in intron 13 (permutation p-values for combined analyses = 0.001-0.003), one in intron 1 (P = 0.004) and one in intron 5 (P = 0.002) with T2DM-associated ESRD. In a subsequent combined analysis of all 1,135 T2DM-ESRD cases and 1,160 controls, an additional 7 intron 13 SNPs produced evidence of association (P = 3.5 x 10(-5)- P = 0.05). No associations were seen with these SNPs in those with T2DM lacking nephropathy or with ESRD due to non-diabetic causes. Variants in intron 13 of the ELMO1 gene appear to confer risk for diabetic nephropathy in AA.

Genome-wide linkage scans for renal function and albuminuria in Type 2 diabetes mellitus: the Diabetes Heart Study.

AIMS/HYPOTHESIS: Glomerular filtration rate (GFR), end-stage renal disease and albuminuria are highly heritable. We performed a genome-wide linkage scan in 416 Diabetes Heart Study (DHS) families to detect loci that contributed to renal function and albuminuria. MATERIALS AND METHODS: A total of 1067 individuals (900 with Type 2 diabetes mellitus) from 348 European American and 68 African American DHS families had measures of urine albumin : creatinine ratio (ACR), serum creatinine concentration and Modification of Diet in Renal Disease estimated GFR (eGFR). Variance components quantitative trait linkage analysis (using SOLAR) was computed. RESULTS: Participants had mean +/- sd age 61.4 +/- 9.4 years; diabetes duration 10.5 +/- 7.4 years; eGFR 1.15 +/- 0.32 ml/sec; and urine ACR 15.8 +/- 67.2 mmol/l (median 1.4). In all families, significant evidence for linkage of GFR was observed on chromosome 2p16 (log of the odds; LOD = 4.31 at 72.0 cM, ATA47C04P/D2S1352) and 1p36 (LOD = 3.81 at 45.0 cM, D1S3669/D1S3720), with suggestive evidence on 7q21 (LOD = 2.42 at 99.0 cM, D7S820/D7S821) and 13q13 (LOD = 2.28 at 28.0 cM, D13S1493/D13S894). The evidence for linkage to ACR was far weaker, on 13q21-q22 (LOD = 1.84 at 50 cM, D13S1807/D13S800), 3p24-p23 (LOD = 1.81 at 58 cM, D3S3038/D3S2432) and 10p11 (LOD = 1.78 at 71.0 cM, D10S1208/D10S1221). CONCLUSIONS/INTERPRETATIONS: The eGFR linkage peaks on 2p16, 7q21 and 13q13 closely overlap with nephropathy peaks identified in family studies enriched for severe kidney disease. These diabetes-enriched families provide an opportunity to map genes regulating renal function, potentially leading to the identification of genes producing nephropathy susceptibility in subjects with Type 2 diabetes.

Loci contributing to adult height and body mass index in African American families ascertained for type 2 diabetes.

Height and body mass index (BMI) have high heritability in most studies. High BMI and reduced height are well-recognized as important risk factors for a number of cardiovascular diseases. We investigated these phenotypes in African American families originally ascertained for studies of linkage with type 2 diabetes using self-reported height and weight. We conducted a genome wide scan in 221 families containing 580 individuals and 672 relative pairs of African American descent. Estimates of heritability and support for linkage were assessed by genetic variance component analyses using SOLAR software. The estimated heritabilities for height and BMI were 0.43 and 0.64, respectively. We have identified major loci contributing to variation in height on chromosomes 15 (LOD = 2.61 at 35 cM, p = 0.0004), 3 (LOD = 1.82 at 84 cM, p = 0.0029), 8 (LOD = 1.92 at 135 cM, p = 0.0024) and 17 (LOD = 1.70 at 110 cM, p = 0.0044). A broad region on chromosome 4 supported evidence of linkage to variation in BMI, with the highest LOD = 2.66 at 168 cM (p = 0.0005). Two height loci and two BMI loci appear to confirm the existence of quantitative trait loci previously identified by other studies, providing important replicative data to allow further resolution of linkage regions suitable for positional cloning of these cardiovascular disease risk loci.

Comprehensive follow-up care and life-threatening illnesses among high-risk infants: A randomized controlled trial.

CONTEXT: Inner-city high-risk infants often receive limited and fragmented care, a problem that may increase serious illness. OBJECTIVE: To assess whether access to comprehensive care in a follow-up clinic is cost-effective in reducing life-threatening illnesses among high-risk, inner-city infants. DESIGN: Randomized controlled trial. SETTING AND PARTICIPANTS: A total of 887 very-low-birth-weight infants born in a Texas county hospital between January 1988 and March 1996 and followed up in a children's hospital clinic. One hundred four infants who became ineligible or died after randomization but before nursery discharge were excluded from the analysis. INTERVENTIONS: Infants were randomly assigned to receive routine follow-up care (well-baby care and care for chronic illnesses; n = 441) or comprehensive care (which included the components of routine care plus care for acute illnesses, with 24-hour access to a primary caregiver; n = 446). MAIN OUTCOME MEASURES: Life-threatening illnesses (ie, causing death or hospital admission for pediatric intensive care) occurring between nursery discharge and age 1 year, assessed by blinded evaluators from inpatient charts and state Medicaid and vital statistics records; and hospital costs (estimated from department-specific cost-to-charge ratios). RESULTS: Comprehensive care resulted in a mean of 3.1 more clinic visits and 6.7 more telephone conversations with clinic staff (P<.001 for both). One-year outcomes were unknown for fewer comprehensive-care infants than routine-care infants (9 vs 28; P =.001). Identified deaths were similar (11 in comprehensive care vs 13 in routine care; P =.68). The comprehensive-care group had 48% fewer life-threatening illnesses (33 vs 63; P<.001), 57% fewer intensive care admissions (23 vs 53; P =.003), and 42% fewer intensive care days (254 vs 440; P =.003). Comprehensive care did not increase the mean estimated cost per infant for all care ($6265 with comprehensive care and $9913 with routine care). CONCLUSION: Comprehensive follow-up care by experienced caregivers can be highly effective in reducing life-threatening illness without increasing costs among high-risk inner-city infants. JAMA. 2000;284:2070-2076.

T cell activation and human immunodeficiency virus replication after influenza immunization of infected children.

BACKGROUND: T cell activation plays a major role in the ability of HIV to remain latent or to establish a productive infection. It has been hypothesized that vaccination-mediated immune stimulation can activate T cells and enhance HIV replication. Our study was designed to determine whether influenza immunization would induce T cell activation and increase HIV burdens in HIV-infected children. METHODS: Blood samples from 16 HIV-infected children ages 6 months to 14 years were obtained immediately before and 2 and 6 to 8 weeks after the administration of influenza vaccine. The percentage of activated (CD25+) T cells was determined by flow cytometry, and HIV viral load was measured by quantitative cultures of peripheral blood mononuclear cells and plasma HIV RNA. RESULTS: The administration of influenza vaccine was associated with significant increases in HIV viral load in 5 of 16 children evaluated. These increases in HIV burden were transient, and in four of five patients the plasma HIV RNA copy number returned to baseline 6 to 8 weeks after immunization. There was no correlation between the patient's immunologic or clinical category according to the CDC classification and either the initial viral load or the likelihood of having a significant increase after immunization. Four of the five patients who experienced increases in viral load after influenza immunization were not receiving antiretroviral therapy. CONCLUSIONS: Our results emphasize the need for additional studies that examine the effect of routine immunizations on T cell activation and HIV replication in HIV-infected children.