Autosomal recessive disorders, such as cystic fibrosis, sickle-cell anemia, and Tay-Sachs disease, which usually occur only when both genes in a pair are defective.
(Tay-Sachs disease; occur only; T:when both genes in a pair are defective; T:usually) (both genes in a pair; are; defective)
Tay-Sachs disease both genes in a pair
occur only are
T:when both genes in a pair are defective T:usually
defective