Maybe it is not the first time you hear that the mistakes of parents come back to haunt their children, but this is exactly the case with the various types of hereditary diseases. There are many types of hereditary diseases, but they all fall under four general categories: single-gene diseases, multifactorial, chromosomal, and mitochondrial diseases.
As the name suggests, single gene diseases (also called monogenetic) have to do with mutations of a single gene in the DNA sequence. This category includes disorders like cystic fibrosis, sickle cell anemia, Marfan syndrome, Huntington’s disease, and hemochromatosis, some of which we will further examine later, although it is comprised or more than 6.000 different types of hereditary diseases overall. Since it is only a single gene that is responsible for the problem, such disorders follow recognizable patterns which are: autosomal dominant, autosomal recessive, or X-linked, meaning disorders that are caused by an abnormal gene located on the X chromosome.
Multifactorial types of hereditary diseases, on the other hand, do not exhibit such a recognizable pattern due to the fact that there many factors that contribute to the disorder: more than one genes, several other problem that could be triggering it, as well as environmental factors. A couple of typical multifactorial disorders are heart defects and neural tube defects.
As for chromosomal abnormalities, they typically the result of some kind of problem of cell division Common types of hereditary diseases in this category are Down syndrome, Turner syndome, and Klinefelter sydrome.
Last but not least, mitochondrial disorders occur due to mutations in the mitochondria, which are the non-chromosomal part of the DNA. MERRF (which is a type of epilepsy), MELAS (a type of dementia), as well Leber’s disease (which is an eye disease), are typical mitochondrial disorders.
Now that you have an idea of these four categories, let us take a closer look at the most widely known types of hereditary diseases. Sickle cell anemia is a blood disorder which causes the production of red blood cells that have the shape of a sickle, instead of the round shape healthy red blood cells have. Marfan syndrome, on the other hand, is a disorder that affects the connective tissue throughout the human body, thus causing a number of problems to the person who has it: long arms and thin fingers, an abnormally short torso, flat feet, a and chest wall abnormalities are the most common. Down syndrome, otherwise known as trisomy 21, is a chromosomal disorder that occurs due to an extra copy of genes in chromosome 21 (hence the name), and it is associated with cognitive impairment (although the degree of impairment may vary), as well as a delay in the individual’s development and certain facial characteristics which stand out. Chances are that you have probably heard about those three types of hereditary diseases, but here are a few more that you should also keep in mind: color blindness, haemophilia, phenylketonuria, Prader-Willi syndrome, cri du chat, Angelman syndrome, Duchenne muscular dystrophy and polycystic kidney disease.