An enzyme aggase requires >16 units of activity for wild type function. Two alleles of aggase have been identified. Wild type allele A_1 produces 12 units of enzyme and mutant allele A_2 produces 5 units of enzyme. Which allele is dominant and which is haploinsufficient? Explain your reasoning. Solution Haploinsufficiency is a potential mechanism in which a diploid species can express a single functional copy of that gene and the other one copy of gene function will be lost due to mutation finally trigger loss-of-function mutation so that it is not possible to generate a complete wild-type phenotype with one functional copy of allele. Therefore, in the above case, enzyme aggase need >16 units of enzyme, in which only A1 generates 12 units & the remaining A2 produced 5 units together 17 units to produce a complete wild-type phenotype. Here, haplosuffciency can occur with a single functional copy of gene, A1 & A2 alleles \"individually\" both are does not produce enough product to meet >16 units of enzyme to display the wild type\'s so that both are considered as haplosufficient Dominance can be observed only in allele A1 because it can mask the allelic recessive locus due to heterozygosity & Mendelian inheritance in which A1 is responsible for the phenotype Other reason: 1. Dominant gain of function in which protein expressed from the mutant gene is constitutively active due to base substitutions finally protein expression is further downregulated because of increase in expression of enzyme proteins. 2. Loss of Function/ Haploinsufficiency: It is also due to loss of heterozygosity thereby by loss of gene function with haploinsufficiency. Finally, resultant organism possesses only one functional gene copy with truncated protein..

1. An enzyme aggase requires >16 units of activity for wild type function. Two alleles of aggase
have been identified. Wild type allele A_1 produces 12 units of enzyme and mutant allele A_2
produces 5 units of enzyme. Which allele is dominant and which is haploinsufficient? Explain
your reasoning.
Solution
Haploinsufficiency is a potential mechanism in which a diploid species can express a single
functional copy of that gene and the other one copy of gene function will be lost due to mutation
finally trigger loss-of-function mutation so that it is not possible to generate a complete wild-type
phenotype with one functional copy of allele. Therefore, in the above case, enzyme aggase need
>16 units of enzyme, in which only A1 generates 12 units & the remaining A2 produced 5 units
together 17 units to produce a complete wild-type phenotype. Here, haplosuffciency can occur
with a single functional copy of gene, A1 & A2 alleles "individually" both are does not produce
enough product to meet >16 units of enzyme to display the wild type's so that both are
considered as haplosufficient
Dominance can be observed only in allele A1 because it can mask the allelic recessive locus due
to heterozygosity & Mendelian inheritance in which A1 is responsible for the phenotype
Other reason:
1. Dominant gain of function in which protein expressed from the mutant gene is constitutively
active due to base substitutions finally protein expression is further downregulated because of
increase in expression of enzyme proteins.
2. Loss of Function/ Haploinsufficiency: It is also due to loss of heterozygosity thereby by loss
of gene function with haploinsufficiency. Finally, resultant organism possesses only one
functional gene copy with truncated protein.