Table 1.

Approximate Probability That a First-Degree Relative of an African American Kidney Recipient Has the APOL1 Risk Genotype, Given Knowledge of the Recipient’s Genotype^*

Recipient’s APOL1 Genotype	Probability That a Relative Has APOL1 Risk Genotype
	Parent	Sibling	Child	Spouse (or Unrelated)
Risk genotype	0.39	0.48	0.39	0.15
Nonrisk heterozygous	0.19	0.13	0.19	0.15
Nonrisk homozygous	0	0.04	0	0.15
Unknown	0.15	0.15	0.15	0.15

APOL1 = apolipoprotein L1 gene.

^*Conditional probabilities were calculated on the basis of autosomal recessive inheritance and a baseline risk genotype frequency of 15% for U.S. African Americans (Supplement, available at Annals.org). The calculations are only approximate, because they assume a single risk allele and all family members self-identifying as African American. Nonetheless, these estimates clearly illustrate large differences in pretest probabilities when the recipient’s genotype is already known.