Hemochromatosis is a condition in which too much iron builds up in the body. When people inherit the condition via their genes, it can be heterozygous or homozygous.
“Heterozygous” means the person only has
In contrast, homozygous hemochromatosis occurs when an individual inherits two copies of genes that cause the condition, which makes them more likely to develop symptoms.
Keep reading to learn more about heterozygous hemochromatosis, including the cause, symptoms, diagnosis, treatment, and answers to common questions.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.
Each person has two copies of every gene. People inherit one set from one parent and the other from the second parent. Each gene has its own functions, such as managing iron absorption.
Heterozygous HH means a person has one healthy gene for managing iron absorption, which they inherited from one parent, but the other copy from the other parent is the gene for HH.
Individuals in this category are carriers, meaning they have a copy of the gene that can pass to children, but they may or may not have any symptoms. Typically, the healthy gene for iron absorption is sufficient to manage this function without problems.
In contrast, those with homozygous HH have
HH occurs due to a difference in a gene known as HFE. This gene regulates the synthesis (production) of the hormone hepcidin, which determines the amount of iron a person absorbs from their diet and how much iron their body releases from storage sites around the body.
Storage sites include the:
- pituitary gland
When a person develops hemochromatosis, it increases their iron absorption from food, even if their dietary intake is typical. Eventually, the storage of iron in cells leads to cell death and the formation of fibrous tissue that affects organ function.
There are several different types of HH gene a person can inherit, and they each affect iron absorption in different ways. The most common in the United States are C282Y and H63D, accounting for
While males and females are equally likely to have HH genes, males are more likely to manifest symptoms and complications. This may be because most females menstruate, meaning they lose iron through blood loss, delaying the onset of symptoms.
Not every person with HH has symptoms, particularly those with only one copy of the associated genes. People with heterozygous HH
In those who do develop symptoms, signs may not show until after
The symptoms of HH can include:
- tiredness or weakness
- erectile dysfunction or loss of interest in sex
- change of skin color, which may look metallic, gray, or bronze
- joint pain, especially in the hands and knees
- pain in the abdomen over the liver
Because people with heterozygous HH
Diagnosing heterozygous HH requires genetic testing. This is because, unlike those with homozygous HH, people with only one copy of a hemochromatosis gene also
To begin the process, a doctor may ask about a person’s medical and family history, particularly about relatives who may have shown signs of HH. If they suspect HH, they refer a person for genetic testing, which may involve taking a blood sample or swabbing inside the cheek.
Alternatively, some companies offer genetic testing for HH via mail-order kits.
Heterozygous HH may not need treatment. However, if a person’s iron level is higher than typical, a doctor may suggest blood draws (phlebotomy).
Phlebotomy is the main treatment for HH. It involves drawing blood through a needle to reduce the iron level. The frequency of this treatment will depend on how much a person’s iron level needs to decrease. After the iron level returns to a typical range, doctors may periodically check it remains within this range.
People who cannot have phlebotomy or who are afraid of needles may benefit from chelation instead. This binds iron that the body then excretes via urine.
Below are answers to some frequently asked questions about HH.
How common is HH?
In the U.S., approximately
What is the difference between homozygous and heterozygous?
“Homozygous” refers to inheriting two copies of a gene, one from each parent. “Heterozygous” means inheriting one copy of a gene from only one parent.
What is the ferritin goal in HH?
Heterozygous hemochromatosis is when a person has one copy of a gene that causes the body to absorb too much iron.
However, an individual with heterozygous hemochromatosis will likely not experience iron overload, nor many symptoms, as they will have one hemochromatosis gene and one healthy gene. The healthy gene can often regulate iron effectively enough on its own.
Heterozygous hemochromatosis does not necessarily require any treatment. However, the gene can pass to children, which will mean they carry it as well. If the other parent also has a gene for HH, there is a higher likelihood that children will have symptoms.
People who suspect they may have genes for hemochromatosis may benefit from speaking with their doctor about genetic testing.