Specific human genetic disorders include cystic fibrosis, Down syndrome, hemophilia, autism and some types of cancer, according to the National Human Genome Research Institute. Additional human genetic disorders include Crohn's disease, thalassemia, sickle cell disease, Parkinson's disease and Marfan syndrome.
All types of genetic disorders are due wholly or partly to a mutation or change in the DNA sequence, states the National Human Genome Research Institute. A genetic disorder occurs through the mutation of one gene or multiple genes as well as through damage to chromosomes and environmental factors, such as cigarette smoking. Genetic disorders fall into three categories: monogenetic disorders, chromosome disorders and multifactorial disorders.
Monogenetic disorders are those that result from a single gene mutation, explains the National Human Genome Research Institute. The mutation may come from the chromosome of one or both parents and pass to offspring. Examples of monogenetic disorders are Tay-Sachs disease and polycystic kidney disease.
Chromosome disorders are due to structural changes in the chromosomes or an excess or deficiency of genes present on chromosomes. For example, Down syndrome is the result of an extra copy of chromosome 21, but there are no abnormal genes present on the chromosome.
Multifactorial disorders are the most common kind of genetic disorder. This type of disorder is the result of small inherited variations of several genes. Often, when combined with environmental factors, illnesses such as heart disease, most cancers and diabetes occur.