Genetic diseases are diseases caused by alterations in genetic material, including chromosomal aberrations as well as genetic mutations. Common genetic diseases include: 1. chromosomal diseases: the most common, such as Down syndrome; 2. monogenic diseases: genetic diseases caused by mutations in one gene, such as congenital deafness, hemophilia, albinism; 3. polygenic diseases: genetic diseases caused by mutations in multiple genes and environmental factors, such as precocious heart disease, cleft lip and palate, anencephaly, spina bifida; 4. mitochondrial diseases: genes in the cell plasma with maternal inheritance.