Practice question

X-linked dominant allele located on X chromosome expresses phenotype even in heterozygous female. Affected father X^A Y transmits X^A containing dominant allele to all daughters via X-bearing sperm, making every daughter affected regardless of maternal genotype, while sons receive paternal Y and are unaffected unless mother also carries trait. This father-to-all-daughters transmission pattern is hallmark of X-linked dominant pedigrees, distinguishing it from autosomal dominant where father passes trait to half offspring irrespective of sex. Affected mothers pass trait to half sons and half daughters.