When a certain gene is known to cause a disease, we refer to it as a single gene disorder. A single-gene disorder is the result of a single mutated gene. Single-gene disorders can be passed on to subsequent generations in several ways. When a couple where one partner or both are sufferers or carriers of a single-gene disorder wish to have a child, they can do so through in vitro fertilization, which means they can then have a preimplantation genetic diagnosis to check whether the embryo has the genetic disorder.
There are a number of inheritance patterns of single gene disorders that are predictable they are.
Most common autosomal dominant disorders are Huntington's disease, Marfan syndrome, charcot marie tooth disease.
Most frequently diagnosed autosomal recessive disorders are cystic fibrosis, Thalassemia, sickle cell disease and spinal muscular atrophy
X-linked recessive disorders are haemophililia and Duchenne muscular dystrophy.
X-linked dominant Rett syndrome and Aicardi syndrome.
Y-linked disorders are caused by mutations on the Y chromosome. These conditions in humans can only be passed from men to their sons; females can never be affected because they do not possess Y-allosomes.