Hereditary diseases are health problems that are passed from parents to offspring through defective genes, according to Steady Health. Some examples of hereditary diseases include hereditary hemochromatosis, Down syndrome, spherocytosis, achondroplasia, Usher syndrome, hemophilia, sickle cell anemia, muscular dystrophy, Turner syndrome, xeroderma pigmentosum, albinism, galactosemia, neurofibromatosis, myotonic syndrome, phenylketonuria, polycystic kidney disease, retinoblastoma, Klinefelter syndrome, Tay-Sachs disease and porphyria.
Genes are responsible for carrying traits from parents to offspring. However, spontaneous or induced mutations may result in defective genes, some of which are responsible for a variety of inherited diseases. For example, Down syndrome is caused by an additional copy of chromosome 21 in humans. According to Steady Health, hereditary diseases can be autosomal recessive (both parents carry faulty genes), autosomal dominant (offspring inherits one healthy gene from one parent and faulty one form the other), polygenic (resulting from multiple genes; for example, hereditary autoimmune diseases), or gender-linked (attributed to either of the sex chromosomes X and Y). Color blindness, muscular dystrophy and hemophilia are sex-linked hereditary diseases.
Individuals can carry genes for certain hereditary diseases and never suffer from the genetic conditions, according to Genetics Home Reference. It is important to seek genetic counseling regarding genetic predisposition to understand the probability of expressing certain hereditary diseases.