Tiêu đề 12 Nov FCPS I Recalls ✅

2 Which of the following best describes a genetic inheritance pattern in which both alleles at a locus contribute independently and equally to the phenotype in heterozygotes? A. Autosomal dominant inheritance B. Incomplete dominance C. Codominance D. X-linked recessive inheritance Correct Answer: C. Codominance Explanation: Codominance refers to a pattern of inheritance where both alleles in a heterozygote are fully and equally expressed. A classic example is the ABO blood group system, where individuals with genotype IAIB express both A and B antigens on red blood cells. Another key example is HLA expression, where both parental alleles are expressed. A = In autosomal dominant inheritance, one mutant allele masks the effect of the normal allele. B = Incomplete dominance results in an intermediate phenotype (e.g., pink flowers from red and white parents). D = X-linked recessive requires two copies of the mutated gene in females or one in males for expression. High-Yield Points: l Codominance: Both alleles are expressed fully and simultaneously (e.g., ABO blood group: A + B → AB).