<prompt> The following are single gene disorders exceptHemochromatosisCystic fibrosisWilliams syndromeHuntingtons disease  <response>: Single-Gene Disorders with Nonclassic Inheritance It has become increasingly evident that transmission of ceain single-gene disorders does not follow classic Mendelian principles. This group of disorders can be clas- sified into four categories: Diseases caused by trinucleotide-repeat mutations Disorders caused by mutations in mitochondrial genes Disorders associated with genomic imprinting Disorders associated with gonadal mosaicism Disorders include : hemochromatosis,cystic fibrosis, Huntington disease Ref Robbins 9e pg 168 