The Family Investigation of Nephropathy and Diabetes Study (FIND)

Inclusion Criteria:

For the Family protocol, proband must meet diagnostic criteria for diabetes and have nephropathy that meets one of the following:

• diabetic nephropathy diagnosed from a kidney biopsy and a history of overt proteinuria.
• ESRD considered due to diabetic nephropathy because
• diabetes is present for ≥ 5 years prior to the initiation of renal replacement therapy and diabetic retinopathy has been diagnosed at any time; or
• diabetes is present ≥ 5 years prior to the initiation of replacement therapy and either a 24 hour urine collection contains ≥ 3 gm protein/24 hours or a random urine protein (mg/dl)/ creatinine (mg/dl) ratio is ≥ 3.0; or
• diabetic retinopathy is present and either a previous 24 hour urine collection contains ≥ 3 gm protein/24 hours or a random urine protein (mg/dl)/ creatinine (mg/dl) ratio is ≥ 3.0.
• nephropathy without ESRD that is considered to be diabetic nephropathy because (a) diabetic retinopathy and a 24 hr urine collection with either ≥ 1 gram proteinuria/24 hours or a urine protein (mg/dl)/ creatinine (mg/dl) ratio ≥ 1.0; or (b) at a time when diabetes duration is ≥ 10 years, either a urine collection of ≥ 3 grams protein/24 hours or a urine protein (mg/dl) /creatinine (mg/dl) ratio ≥ 3.0.

African-American patients with chronic renal failure are as MALD cases by meeting criteria for diabetic nephropathy, as described for Family probands, or having nephropathy (serum creatinine ≥ 2.0 mg/dl) not due to diabetes or known monogenic renal disease. Mexican-Americans recruited as MALD cases must meet criteria for diabetic nephropathy as defined for the Family probands. Phenotype criteria for probands entered into the Family or MALD protocols must be confirmed by medical record review.

Eligibility of family members and MALD control subjects is based on laboratory tests obtained at the time of screening. Entry of a proband with diabetic nephropathy into the Family protocol also requires participation of either two living parents or at least one full sibling with diabetes. To be enrolled as having nephropathy, the diabetic sib must meet one of the following criteria:

• renal biopsy consistent with a diagnosis of diabetic nephropathy;
• urinary albumin excretion ≥ 30 mg/24hr or a urine albumin (mg/dl)/creatinine (mg/dl) ratio ≥ 0.03;
• a serum creatinine concentration ≥ 1.6 mg/dl for men or ≥ 1.4 mg/dl for women; or
• ESRD. Unaffected sibs are recruited if they have had diabetes for ≥ 10 years, have normal serum creatinine and albumin excretion (< 30 mg albumin/24 hours, or a urine albumin (mg/dl)/creatinine (mg/dl) ratio < 0.03) and no historical evidence of kidney disease.

The criteria for MALD control subjects differ by ethnic group. For the African-American MALD protocol, two different control samples are recruited. First, an adult offspring with or without renal disease and the other parent of the offspring, who cannot have evidence of renal disease, are collected as controls for African-American probands with either diabetic or non-diabetic nephropathy. Together with the probands, this forms a sample of triads (offspring and other parent) or dyads (spouse only). A second group of African-American control subjects consists of unrelated individuals with diabetes duration ≥ 10 years and without nephropathy (as defined above for diabetic sibs). For Mexican Americans, a single unrelated control population is recruited with diabetes duration ≥ 10 years but without nephropathy (as defined above for diabetic sibs).

Exclusion Criteria:

A. Did not sign the informed consent: refusal to participate. B. Diagnosis not confirmed. C. Appropriate siblings not available. D. Judged not likely or unable to follow study protocol. E. Ethnicity of parents or grandparent not suitable. F. Spouse not available.