Total Hexosaminidase
Noncarrier: 589–955 nmol/hr/mL; SI units: 9.9–15.9 U/L
Heterozygote: 465–675 nmol/hr/mL: SI units: 7.8–11.3 U/L
Tay-Sachs homozygote: >1027 nmol/hr/mL; SI units: >17.2 U/L
Hexosaminidase A
Noncarrier: 456–592 nmol/hr/m; SI units: 7.2–9.9 U/L
Heterozygote: 197–323 nmol/hr/mL; SI units: 3.3–5.39 U/L
Tay-Sachs homozygote: 0 nmol/hr/mL; SI units: 0 U/L
Hexosaminidase B
Noncarrier: 12–32 nmol/hr/mL; SI units: 0.2–0.54 U/L
Heterozygote: 21–81 nmol/hr/mL; SI units: 0.35–1.35 U/L
Tay-Sachs homozygote: >305 nmol/hr/mL; SI units: >5.1 U/L
. Red-top tube
■ Hexosaminidase is an enzyme necessary for metabolism of
gangliosides. Deficiency results in accumulation of
gangliosides in the brain.
■ Used to diagnose Tay-Sachs disease, which is caused by a lack
of hexosaminidase A and results in mental retardation,
blindness, weakness, and death by age 5.
■ Sandhoff’s disease is a variant of Tay-Sachs and results from a
deficiency of both hexosaminidase A and B.
