SNP Shot: Genomic Insights

Hereditary hemochromatosis is a condition where the body absorbs and stores excessive amounts of iron from food. This excess iron accumulates in various tissues and organs, including the skin, heart, liver, pancreas, and joints. Because the body has limited ability to eliminate iron, this buildup can lead to organ damage and dysfunction. Consequently, hereditary hemochromatosis is also known as iron overload disease.

Early signs of hereditary hemochromatosis may include extreme fatigue, joint and abdominal pain, unexplained weight loss, and a decreased libido. As the condition progresses, individuals may experience arthritis, liver problems such as cirrhosis or liver cancer, diabetes, heart problems, or skin discoloration. The severity and presentation of these symptoms can be influenced by dietary iron intake, alcohol consumption, and the presence of infections.

Hereditary hemochromatosis is categorized into four types, differentiated by factors such as the age of onset, genetic causes, and inheritance patterns.

Type 1, the most prevalent form, and type 4 (ferroportin disease) typically manifest in adulthood. Men with type 1 or type 4 hemochromatosis usually exhibit symptoms between 40 and 60 years of age, while women commonly develop symptoms after menopause.

Type 2 hemochromatosis is considered a juvenile-onset disorder because symptoms often appear during childhood. By the age of 20, iron accumulation can lead to reduced or absent production of sex hormones. Affected females typically begin menstruation normally, but their menstrual cycles cease after a few years. Males may experience delayed puberty or symptoms associated with insufficient sex hormones. Without treatment, type 2 hemochromatosis can cause life-threatening heart disease by age 30.

Type 3 hemochromatosis has an onset that falls between types 1 and 2, with symptoms generally appearing before the age of 30.

Inheritance:

Types 1, 2, and 3 hemochromatosis follow an autosomal recessive inheritance pattern. This means that both copies of the responsible gene in each cell must carry a mutation for the condition to develop. Typically, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene but do not exhibit symptoms themselves. Type 4 hemochromatosis, in contrast, exhibits an autosomal dominant inheritance pattern. In this case, only one copy of the altered gene in each cell is sufficient to cause the disorder. Often, an affected individual has one parent who also has the condition.