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X-linked genetic conditions

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

Genetic conditions can be passed on from either the mother’s line or the father’s. We each inherit two chromosomes, from our mother and father, that determine our sex – women have XX chromosomes and men have XY.

A female has two X’s, so if one has a genetic disease, she may not show the characteristics as she can rely on the healthy X chromosome. She can, however, pass the disease on to the next generation. She is known as a carrier.

A male, on the other hand, only has one X chromosome – if this is faulty, he will display characteristics of certain syndromes or conditions. He is known as a sufferer.

The two sex hormones are just one pair of 23 chromosome pairs. Genetic conditions can be inherited from any of these and may be unrelated as to whether it’s your mother or father who has a disease.

Doctor’s advice

What is an example of an X-linked condition?

An example of an X-linked condition is haemophilia, where the usual process to clot blood is impaired. This can have life-threatening implications from the knocks and tumbles of the school playground to even the most minor of surgical procedures, such as having a tooth out. Life is not impossible, but just needs modifications and certain precautions.

Only men who inherit this are badly affected. Women are either only mildly affected or pass it on to their male children.

New advances in fertility planning can offer the opportunity to ensure that future generations do not inherit these faulty genes. X-linked conditions are not contagious, they are passed down to your children in your genes. For people who are not planning on conceiving, it is important to consider a form of contraception, such as a condom or a daily contraceptive and in case of an emergency, the emergency contraceptive.

When should I see my doctor?

If you or your partner suffers from one of these conditions and you are planning a pregnancy, discuss this with your doctor or any specialist involved in your condition, to consider any risks or reduction of risks to your planned family.

Am I fit for work?

Fitness to work with a genetic condition depends on the particulars of your diagnosis.

Other X-Linked genetic conditions

Duchenne Muscular Dystrophy (DMD): DMD is a progressive muscle-wasting disorder caused by mutations in the dystrophin gene. It primarily affects boys, leading to muscle weakness and degeneration.

Hemophilia A and B: Hemophilia is a bleeding disorder where blood clotting is impaired. Hemophilia A is caused by a deficiency of clotting factor VIII, while Hemophilia B is caused by a deficiency of clotting factor IX.

Red-Green Color Blindness: The most common form of color blindness, affecting the ability to perceive red and green colors, is often linked to the X chromosome. While females can be carriers, males are more commonly affected.

X-Linked Agammaglobulinemia (XLA): XLA is a primary immunodeficiency disorder caused by mutations in the BTK gene. It leads to a lack of mature B cells and antibodies, making individuals more susceptible to infections.

Rett Syndrome: Rett syndrome is a neurological disorder that predominantly affects females. However, rare cases of males with Rett syndrome have been reported. It is caused by mutations in the MECP2 gene.

Fragile X Syndrome: Fragile X is the most common inherited cause of intellectual disability. It is caused by the expansion of the CGG trinucleotide repeat in the FMR1 gene on the X chromosome.

Muscular Dystrophy (Becker): Similar to Duchenne Muscular Dystrophy, Becker Muscular Dystrophy is caused by mutations in the dystrophin gene. It usually has a later onset and milder progression than DMD.

Androgen Insensitivity Syndrome (AIS): AIS is a condition where individuals with XY chromosomes are partially or completely insensitive to androgens, resulting in varying degrees of underdeveloped male sexual characteristics.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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