A Genetic Cause for Iron Deficiency: We see a... - Thyroid UK

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A Genetic Cause for Iron Deficiency

helvella profile image
helvellaAdministrator
9 Replies

We see a steady stream of posters here who have iron-deficiency. Iron-deficiency is an important issue in hypothyroidism. Hypothyroidism can reduce our ability to absorb iron. Low iron (typically low to very low ferritin) prevents thyroid hormone being handled well by the body.

Many times, low iron can be addressed by a suitable iron supplement, often adding vitamin C (ascorbic acid) to help with absorption. As I have said many times, in addition to the standard iron supplements (sulphate, bisglycinate, fumarate, etc.) some people do better on supplements based on haem (heme) or ferritin.

Despite identifying iron deficiency, and taking supplements (often trying several), even having infusions or transfusions, some people remain iron deficient.

Hence, I thought the article below might be of interest to some.

Do take particular note that, despite appearing to have identified a genetic issue, the precise details are still being analysed. There could be many subtly different genetic differences and their effects could well vary from one individual to another.

Also, don't assume this interesting possibility applies to you unless and until you have proved it by a genetic test. It is so very easy to think it makes sense and explains our issues but it could be something else. Quite possibly even if your issue does have a genetic cause, it might not be this one!

A Genetic Cause for Iron Deficiency

Rare syndrome may provide general insight into iron deficiency

The discovery of a gene for a rare form of inherited iron deficiency may provide clues to iron deficiency in the general population – particularly iron deficiency that doesn’t respond to iron supplements. The finding was published online by the journal Nature Genetics on April 13.

Iron deficiency is the most common nutritional deficiency and the leading cause of anemia in the United States, according to the Centers for Disease Control and Prevention. Most cases are easily reversed with oral iron supplements, but over the years, Mark Fleming, interim Pathologist-in-Chief at Children’s Hospital Boston, and pediatric hematologist Nancy Andrews, formerly of Children’s Hospital and now Dean of Duke University School of Medicine, had been referred a number of children with iron deficiency anemia who didn’t respond to oral supplements, and only poorly to intravenous iron.

The cause of their condition – termed iron-refractory iron-deficiency anemia (IRIDA) – was a mystery. The children all had good diets, and none had any condition that might interfere with iron absorbtion or cause chronic blood loss, the most common causes of iron deficiency anemia. Seeing reports of several similarly afflicted families in the medical literature, Flemming and Andrews were convinced that genetics was a factor.

“After nearly 15 years, we finally had enough families that we could begin to think about positionally cloning the gene for the disorder,” says Fleming, who is also an associate professor of pathology at Harvard Medical School.

Fleming and Andrews, experts in iron metabolism, and their colleagues Karin Finberg and Matthew Heeney, studied five extended families with more than one chronically iron-deficient member. They found a variety of mutations in a gene called TMPRSS6 (the acronym stands for transmembrane serine protease S6) in all of these families, as well as several patients without a family history of the disorder.

Although IRIDA is quite rare, the authors believe it might be the extreme end of a broad continuum of disease, since TMPRSS6 mutations varied widely in the five families and caused different degrees of iron deficiency and anemia.

“Our observations suggest that more common forms of iron deficiency anemia may have a genetic component,” says Andrews.

All patients in the study apparently had recessive mutations, since their parents did not have iron deficiency anemia. The investigators now want to determine whether people with just a single abnormal copy of TMPRSS6 have subtler alterations in iron absorption that might not otherwise have come to the attention of a hematologist.

Although the mechanism is still unknown, deficiency of the TMPRSS6 protein causes the body to produce too much hepcidin, a hormone that inhibits iron absorption by the intestine. Normally, hepcidin is produced to protect the body against iron overload- but patients with IRIDA make large amounts of hepcidin even through they are iron deficient. “People with this disorder make too much hepcidin, putting the brakes on iron absorption inapropriately,” Fleming says.

In addition, patients with TMPRSS6 mutations cannot make new red blood cells efficiently because the iron needed to make them comes from macrophages, and hepcidin causes macrophages to hold on to iron. This explains the patients’ poor response to intravenous iron – the iron is trapped in macrophages and cannot be used for red blood cell production.

The fact that TMPRSS6 regulates hepcidin may open up new avenues for therapy, the researchers say. For example, blocking TMPRSS6 may help patients with iron overload disorders make more hepcidin in order to limit intestinal iron absorption. Conversely, stimulating TMPRSS6 may have therapeutic benefit in certain patients with anemia, particularly those in which hepcidin is overproduced.

The study was supported by the National Institutes of Health.

news.harvard.edu/gazette/st...

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helvella
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shaws profile image
shawsAdministrator

Thanks helvella for this information on iron.

It is surprising what a difference an addition can make for those who may have been unaware of their deficiency.

DippyDame profile image
DippyDame

Thank you helvella

Very interesting.

I guess we have much still to learn from genetics....it's a bit like walking through a maze

Your comments could equally refer to thyroid genetics; a geneticist once told me, " we just don't know....yet".

I recently discovered that I have a very rare deletion....passed on to my older son and his younger son. Not sure if mine is maternal or paternal....in a bit of a daze at the time I forgot to ask. Guess I still can!

The little one was very ill after he was born.....now, thanks to a brilliant Italian surgeon , he is a gorgeous bright lively 4 year old planning his own university astrophysics research like Daddy!! "Pluto is my favourite planet" as he reels off info.

Lost Granny at the starting gate!

Sorry, I digress, back to the subject! I 've just started taking Spatone again, it's the only "iron" that I can tolerate....just in case anyone reading has problems with supplements. It's worth a trial

Ranting again.....washing to hang out. Sunshine!

Best...

DD

helvella profile image
helvellaAdministrator in reply toDippyDame

Digress (almost) to your heart's content. :-)

Have you actually tried haem source iron? Or ferritin-based products?

The reason I keep banging on about them is that we have (at least) three separate iron absorption pathways. One for general iron, one for haem, and one for ferritin. They can all three operate independently. That is, you could "max out" one but still have absorption capacity for the others.

Further, haem and ferritin rarely cause the stomach/gut issues so often reported from the basic iron supplements like ferrous sulphate.

DippyDame profile image
DippyDame in reply tohelvella

I'm afraid I only used the "difficult ones" before Spatone .....it seems OK but I'm due to test soon so we'll see.

Looks as if I need to do more homework... I did not know about the different absorption pathways!

Your good advice appreciated as always

DD

PS I promise not to fly too far from the topic!!!

helvella profile image
helvellaAdministrator in reply toDippyDame

:-)

Ages ago, I put together some information about iron but have NOT kept it up to date.

dropbox.com/s/4d885frbic4z8...

Read with a large pinch of salt - posted primarily for the link to the info. re iron absorption pathways.

Mostew profile image
Mostew in reply toDippyDame

Do!! Fly . Have wings

humanbean profile image
humanbean

Thanks for this post, helvella, it's very interesting.

I have long suspected that my family has genetic problems with iron absorption - not bad enough to prevent iron absorption altogether, but enough to slow things down a huge amount. I know of seven blood relatives who have issues with regular anaemia or iron deficiency in my own immediate family, in an aunt's family, and in an uncle's family. The fact that two of the seven sufferers are male makes it unusual, I think.

helvella profile image
helvellaAdministrator in reply tohumanbean

That is exactly the type of cases/group of cases that I was referring to.

Yes, it is odd. Yes, it does need further investigation. Until now, a genetic basis might have been considered by some but with no evidence as to where anyone should look.

Mostew profile image
Mostew

Thank you . Sorting Health challenges is never straightforward !!!

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