APOL1 Genotyping
Gene: APOL1
Protein: apolipoprotein L-1
Clinical Characteristics
APOL1 variants are associated with increased susceptibility to focal segmental glomerulosclerosis (FSGS4; OMIM 612551) when two risk alleles are present.
Focal segmental glomerulosclerosis is clinically associated with:
- Proteinuria
- Nephrotic syndrome
- Progressive loss of renal function leading to end-stage renal disease
Individuals of African descent are at a greater risk to develop chronic kidney disease than individuals of European descent. Studies have shown that specific variants in APOL1 confer nearly all of this increased risk. These variants, classified as G1 and G2 are prevalent in African Americans, and have not been identified in European Americans.
APOL1 variants are also associated with increased risk of hypertension-attributed end stage renal disease, sickle cell-associated kidney disease, and shortened graft survival of kidney transplants based on the donor genotype.
Inheritance pattern: Autosomal recessive
What Can Be Learned From This Test
Identification of two risk alleles in one individual is associated with an increased susceptibility to focal segmental glomerulosclerosis and other types of kidney disease.
Some studies indicate that donor kidneys harboring two APOL1 risk variants failed more rapidly after transplantation than those kidneys with zero or one risk variant.
Testing is performed by bi-directional sequencing of exon 6 of APOL1 (NM_145343.2). This test will determine the presence or absence of the G1 and G2 alleles.
Sample Requirements
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 10-14 business days
CPT Codes and Cost
Genotyping
Code: 81479
Cost: $225
Known Variant TestingÂ
Code: 81479
Cost: $225