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How are autosomal recessive gene mutations passed down through the family?

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4 fertility expert(s) answered this question

Answer from: Maria José Mendiola, MD, MSc in Human Genetics, MSc in Science Communication, ObGyn

Gynaecologist, Gynaecologist in Reproductive Medicine & Reproductive Genetics Clínica Monterrico
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Autosomal recessive inheritance variance is secured in both copies of the gene in each cell – in both copies, not just in one. So the parents of an individual with an autosomal recessive condition, each carry one copy of the ultra gene but they typically do not show signs and sepals of the conditions that is why it is recessive. Autosomal recessive disorders are typically not seen in every generation of an affected family so, they will have a 25% (one in four) chance of having a child affected by the condition. Additionally there is a 50% chance that their child will be an effective carrier.

Answer from: Maria José Mendiola, MD, MSc in Human Genetics, MSc in Science Communication, ObGyn

Gynaecologist, Gynaecologist in Reproductive Medicine & Reproductive Genetics Clínica Monterrico
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We have some scenarios: in one scenario if the mother is a carrier of a x-linked recessive gene variant, we have the chances of a mother who is a carrier of a x-linked recessive gene variant having a child with a condition are different for her sons and daughters, for example, we have here a non-working x-linked recipient copy and we have a working copy. The mother is a carrier of an x-linked recessive gene health condition and the father has only a working copy of the gene so, there are four possibilities in every pregnancy that the child can receive from their parents for such a couple – this means that in every pregnancy, there is one chance in four, 25% chance that a son will inherit the Y chromosome from their father and x-linked recessive not work gene copy with the variant from the mother. In this case, the battle cells cannot make gene products in the right way. This person will therefore have the condition. On the other hand, one in for 25%, we have a chance that a son will inherit the Y chromosome from their father and the working copy of the x-linked gene from the mother so, this person will therefore not have the condition and on the other hand we have a 25% chance (one in four) for example, that the daughter will inherit both working copies of the x-linked genes (one copy from the father and one from the mother) so, in this case, a daughter will therefore be unaffected by the condition. In addition, they will also not be a carrier of the x-linked recessive copy with the variant and finally, we could have a chance at 25% (one in fourth) I could have a daughter that could inherit from their father the working copy of the X-linked gene and the x-linked recessive non-working gene copy variant from the mother – this person will be a genetic career condition like the mother and will usually be unaffected. Ao to sum up, if pregnant with a son there is a 50% chance that the child will have the condition and if pregnant with daughter, we have a 50% chance that they will be a genetic career of the condition but on the other hand what could happen if the father is affected by an x-linked recessive gene condition, in this case, if the father is affected by an x-linked recessive genetic condition, the chance of passing on the non-working recessive gene copy is different for his sons and daughters. We could have two possibilities in every pregnancy that we should explain to our patients: the child can receive from the parents, for example, the father passes his Y chromosome to his sons and the father passes his X chromosome to his daughters for such a couple this means that in every pregnancy all sons will inherit the working X-linked gene copy from their mother and the Y chromosome from their father will therefore not have the conditions but all the others will inherit a working copy of the x-linked gene from their mother on x-linked recessive gene variant from their father so, they will be carriers of the variant and can pass this on to their children’s they will usually in this case not have the condition.

Answer from: Douglas Lester, PhD, MSc, BSc (Hons)

Geneticist, Co-Founder & Chief Scientific Officer Fertility Genomics
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Most families don’t realize they have a recessive condition because a lot of the members are just carriers and unaffected. It’s only detected if a person is unlucky enough to marry a person with a recessive mutation of the same gene. It depends on your population group; cystic fibrosis is very common if you’re Northwest European. It is not so common in other groups. If you are of Western European origin ancestry, then they do carriers screening routinely for cystic fibrosis. 1 in 3,000 births is cystic fibrosis in that population. If you’re of Afro Caribbean origin, then sickle cell and thalassemia are very common. As many as 1 in 10 people can be carriers of sickle cell or thalassemia in that population. If you’re of Jewish ancestry, there is Tay Sachs disease. There’s a large Jewish population in Johannesburg, 114,000 Jews. 1 in 30 of them is a carrier of Tay Sachs disease. In this horrible crippling disease, the child is born, and it accumulates fat on the brain, and the child usually dies at the age of four. It’s an honorific disease, but the Jewish population is very aware of that and usually gets tested even before marriage.

Answer from: Glykeria Samolada, Biologisst, MSc. Mol. Cytogenetics

Geneticist, EuR Genetic Counsellor
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Autosomal recessive describes the way some genetic changes are or can be inherited. Autosomal means that the change is in an autosome, one of the sex chromosome and recessive means that features or symptoms can be observed only when both copies of chromosomes or genes are affected. We inherit 2 mutated genes: one from each partner and this disorder is passed only by two carrier parents. Their health is rarely affected as they have one mutated gene and one normal gene. Two carriers have 25% chance of unaffected child and 2 normal genes and 50% chance of having unaffected child who also is carrier and 25% chance of having an affected child with 2 recessive genes. The list of the autosomal disorders include disorders like cystic fibrosis and spinal muscle dystrophy.

About this question:

How do we inherit autosomal recessive gene mutations?

If only one parent suffers from an autosomal recessive gene mutation, will the child inherit the gene? What is the difference between a gene carrier and a person affected by the mutation?

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