Inheritable Gender Related Illnesses

Factual Questions
1

Do they depend on maternal vs. paternal lineage?

IOW, suppose someone has a history of breast cancer in the family, she is at increased risk of getting it herself. Does it make a difference if the history is on her mother’s side or father’s side?

Three possibilities: either it is not an increased risk at all if it is from the father’s side, or it is the same risk as if it is on her mother’s side, or it is an increased risk in any event but a greater increase if it is on her mother’s side.

I bring up this specific example because my wife has asked a couple of doctors about it and gotten contradictory answers. But I imagine the same could be asked of other illnesses that are gender related (possibly with different answers), hence the title.

2

Unless you’re talking about disorders linked to genes on the X chromosome (like hemophilia or colorblindness), no, it doesn’t matter. (There’s an exception; a group of very rare diseases are affected by ‘imprinting’, in which the body knows which copy of a chromosome came from which parent. The resulting disease from a defective gene thus varies depending on whether it came from mom or dad. One example of this is Praeder-Willi (sp?) disease. But for the diseases that most people worry about, the answer’s no.)

Even though men get breast cancer (to take your example) very very rarely, they still carry genes relating to it, and pass them on to their children. However, when calculating the risk of breast cancer, doctors use a formula that (IIRC, since I’m not a doctor) mostly counts first degree relatives, such as one’s mother and sisters. Grandmothers, aunts, and other relatives don’t really influence the calculations much, so paternal relatives aren’t going to affect the outcome.

3

Depends. There are disorders that can be inherited on the autosomal (non-sex) chromosomes - these can be inherited from both parents, and if recessive (as most are) need to be inherited from both.

If the disorder is dominant, only one copy needs to be defective; if it’s recessive, both copies need to be.

X-linked diseases (females are XX, males are XY) are inherited, by females, the same way as autosomal diseases: from either parent if dominant, from both if recessive. For males (who are XY), an X-linked disease will be inherited only from the mother (X comes from mom, Y comes from Dad) and it only takes one copy whether the disease is dominant or recessive. This is why X-linked diseases strike boys more often than girls: the boy will have the disease if he gets one bad copy; the girl won’t have a problem unless she has two bad copies.

If a disease is Y-linked, only males can get it, and it will pass in a strict father-to-son lineage, but I don’t know of any that work that way. The Y chromosome is very small, only about 200 genes (compared to 1500-ish on Chromosome 1)

There is mitochondrial inheritance - this is an extra set of chromosomes that pass from mother to children of both sexes - but I don’t know of any diseases that are transmitted this way.

There are a few things, like shell coiling in snails (I think there may be something controlled this way in humans) that depends on the mother’s genes and not at all on the child’s (it affects what the mother does to the egg, which the child’s genes have no say in).

One last thing: the DNA is treated differently in male and female gonads, through something called methylation. This is probably what occurs in certain diseases that differ depending on what parent they cam from. There is a gene that causes Prader-Willi syndrome if you get it from your father, but Angelman syndrome if you get it from your mother.

GilaB is right about the role of males in BRCA and other autosomal genes: even if a male doesn’t have the disease, he still has the genes. Remember that the BRCA genes are an additional factor, but only in some cancers, and they’re far from the whole stories. There have been a lot of studies recently showing that it’s not a very good idea to remove body parts preemptively based only on family history. Of course, I’m not a doctor (just a student of biology) so don’t mistake this for medical advice.

4

There are a few, involving disorders of energy use and metabolism. They’re very rare, but they do exist.

And certainly if your father had breast cancer you’re considered at greater risk, your father being a first degree relative. In fact, if several of your male relatives had breast cancer it would be a strong indication there’s an inherited tendency towards it in your family, since it’s so rare in men.

Although if you DO have one of the the identified breast cancer genes prophylactic removal of the breasts and ovaries can reduce the chances of a woman getting cancer. But it never reduces the risk to zero, and it’s not to be done lightly. For this minority of women, doing just that might make sense once they are done with any childbearing they wish to do. But most woman with breast cancer do NOT have one of these specific genes.