Ok I have been wondering this a LONG time. Do the children of an PHD person usually have the same hair and eye color and have similar features? Or can it affect any of the children the same? Because HD is a genetic disease and hair and eye color are genetic....? Just always wondered that!

For example- PHD mother has blonde hair and blue eyes...but has 2 daughters that favor the fathers look more and have brown hair and brown eyes and 1 son that has blonde hair and blue eyes and favors the mothers looks more.
is the son more likely to have HD than the daughters because he looks more like the Mother?

This is just an example......I have always wondered this.

No, there is no connection between which parent the child resembles in looks and whether or not they inherited the HD gene.

The gene for the protein huntingtin is on chromosome 4. Human eye and hair color genes are on other chromosomes and therefore should sort totally independent of hd. Sharing such traits with a phd parent should therefore imply no greater likelihood of sharing hd.

There is one gene on chromosome 4 associated with red hair but it is too far from the huntingtin locus to have appreciable inheritance linkage.

My Phd looked exactly like his dad, but inherited the gene from his Mom.

There is one gene on chromosome 4 associated with red hair but it is too far from the huntingtin locus to have appreciable inheritance linkage. Can you explain this in a simple way? What is locus? =)

That is something that I have also wondered about. Since all 3 kids resemble me I was hoping that they would have less of a chance, but I guess not.

papple_juice: locus is just the technical term for the location of the gene on the chromosome. Your cells each have two copies of chromosome 4, one from your father and the other from your mother. Germ cells (eggs and sperm) have only one copy of chromosome 4 (representing about 6% of your total genes). That one copy has some stretches from your mother's chromosome and some from your father's thanks to a process called crossover. If my memory serves me right, a typical germ cell chromosome may have resulted from about 6 to 20 crossovers on average. The distance between the red hair gene I mentioned and the huntingtin gene is about a third of the total length of chromosome 4. That interval would have about 2 to 7 crossovers on average making the linkage between the two genes about the same as if they were on unrelated chromosomes.

Very few outwardly-observable human traits have simple genetics and none of those (except the red hair gene I mentioned) are on chromosome 4. Blood type is on chromosome 9. Perhaps in the future some trait may be traced to a locus near enough to the huntingtin locus to allow such inferences but until then, Marsha is right, there is no connection,.

wow. In my family ALL the PHD has been blonde hair blue eyes or red hair green/blue eyes. My mother had blonde/blue and I have brown/brown. Wonder if that is the red hair gene thing you spoke of......just curious.



Edited 1 time(s). Last edit at 11/03/2011 08:38AM by papple_juice.

judy me too. all phd in my family had red or blonde hair.....so i was hoping that my sister and i didnt have it bc we look more like our father....but i guess not.

no it doesn't work that way, I take after my father that died of HD, my brother is like my mother. I ended up testing negative,and my brother has HD.

I am so sorry to hear that about your brother cookie. =( I hope he is doing good. When did you get tested? Were you having symptoms of HD?