Single gene disorder which does not follow Mendelian inheritance -

Transmission of certain single-gene disorders does not follow classical Mendelian principles. This group of the disorder can be classified into the following categories - Diseases caused by triplet - repeat mutation, e.g. fragile - X syndrome, Huntington disease, & others. Disorders caused by a mutation in mitochondrial genes, e.g. labour hereditary optic neuropathy. A disorder associated with genomic imprinting. Disorders associated with gonadal mosaicism.