Expression of the A and B antigens on red blood cells is influenced by the FUT1 gene. This gene encodes fucosyl transferase, an enzyme that helps produce the H substance. Which of the following statements about the H substance is incorrect?

Individuals that cannot produce the H substance appear to be type O even if they have functional A and/or iB alleles.
Individuals that fail to produce the H substance are said to have the Bombay phenotype.
Individuals that are heterozygous for the FUT1 gene cannot produce the H substance
The H substance is a substrate for the enzymes produced by the n and β genes. These enzymes add the appropriate terminal sugar to the H substance producing the A and B antigens, respectively. ︵

The following statements about the H substance that is incorrect is

(Individuals that are heterozygous for the FUT1 gene cannot produce the H substance)

Explanation: substance H is found on virtually all the red blood cells. FUT1 gene encodes fucosyl transferase, an enzyme that helps produce the H substance. They are used as precursor for the formation of A and B antigens. From the statements;

-Individuals that cannot produce the H substance appear to be type O even if they have functional A and/or iB alleles, Is a correct statement.

-Individuals that fail to produce the H substance are said to have the Bombay phenotype. This is a correct statement.

-The H substance is a substrate for the enzymes produced by the n and β genes.

- These enzymes add the appropriate terminal sugar to the H substance producing the A and B antigens, respectively.

But if a person carries even a single functional copy of FUT1 gene, that is, heterozygous or homozygous then he or she can efficiently produce H antigen. Therefore (Individuals that are heterozygous for the FUT1 gene cannot produce the H substance) is an incorrect statement.