Which description matches homozygous recessive FH?

• A. FF; defective LDL receptors; LDL levels above 600 mg/dL
• B. Ff; 50% defective LDL receptors; LDL levels 300-350 mg/dL
• C. ff; normal LDL receptors; LDL levels below 100 mg/dL
• D. FF; 2 defective LDL genes; LDL levels above 600 mg/dL

Answer: (C)

Understanding how a recessive genetic pattern maps to a phenotype helps explain why the two recessive alleles would show a normal LDL profile in this item. When a trait is recessive, you need two copies of the recessive allele to express that specific phenotype. If having two recessive alleles for the FH gene corresponds to functioning LDL receptors in this question’s framing, the result would be normal receptor activity and thus LDL levels that are low (below 100 mg/dL). That’s why the description with two recessive alleles and normal LDL receptors aligns with the idea of a homozygous recessive genotype producing a normal, non-FH phenotype. The other options describe scenarios with defective LDL receptors and very high LDL levels, which reflect a state where receptor function is compromised, not the two-recessive-allele, non-FH state.