Familial hypercholesterolemia, or FH, is a genetic disorder that affects the body’s ability to remove LDL, or “bad” cholesterol, from the bloodstream, leading to dangerous buildups of plaque in the blood vessels and the serious cardiovascular problems that can result. To understand how FH is passed down through generations, you need to know the answer to this question: what is a genetic disorder? These are the basic facts about how genetic disorders like FH work.
What is a Genetic Disorder?
A genetic disorder results from mutations in an individual’s DNA, which occurs when a gene’s sequence is altered. They can be extremely serious because genes code for proteins, the molecules that make up the majority of cellular structures and are responsible for most of the body’s life functions. A gene that mutates produces proteins that cannot perform their intended functions. While genetic diseases can result from changes in DNA in somatic cells due to environmental factors, they are most often thought of as inherited conditions, since the genetic information is passed from parents to their children.
What Causes a Genetic Disorder?
The three main ways a genetic disorder can be caused are single-gene mutation, chromosomal error, and multifactorial cause. Genetic disorders that are caused by single-gene mutation are called Mendelian disorders, caused by an error in just one DNA sequence. Huntington’s disease and cystic fibrosis are two well-known genetic disorders that are caused in this way. This type of genetic disorder is extremely rare, occurring in typically one out of many thousands or millions of people.
Multifactorial genetic disorders, on the other hand, are caused by mutations in several genes that can be compounded by environmental factors. Though this sounds more complicated, multifactorial genetic disorders and diseases are actually more common. Cancer, for example, is a genetic disease that can be caused by random or environmentally triggered mutation. However, diseases like breast cancer that are most often caused by genetic alterations to a certain amount of an individual’s cells also have rare hereditary forms.
Chromosome disorders are caused by an excess or deficiency of the genes located on chromosomes or structural changes within chromosomes. Down syndrome is a common chromosome disorder that occurs when an individual has an extra copy of one particular chromosome, but all the genes on the chromosome are normal.
What is a Genetic Disorder that is Hereditary?
Hereditary genetic disorders are passed down through a family. Like other inherited traits, genetic disorders can be recessive or dominant. If a genetic disorder is recessive, the individual must inherit the mutated gene from both parents to get the disorder or disease. If it is dominant, only one parent needs to pass the mutated gene down to the child for the genetic disorder to manifest. FH is a dominant genetic disorder, so only one parent needs to pass the mutated gene down. However, if both parents pass it down, the child will have homozygous FH, a far more serious form of the disorder.
For more information about genetic disorders, FH, and how you can get involved, contact the FH Foundation.