I understand that the X-chromosome is responsible for certain disorders, like red-green colorblindness; but besides disorders, what do the genes on the X-chromosome determine?


closed as too broad by canadianer, Remi.b, kmm, mgkrebbs, Bryan Krause Mar 16 '18 at 18:28

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    $\begingroup$ The number of genes on the X chromosome approaches 1000 and thus your question is too broad for this site. $\endgroup$ – canadianer Mar 16 '18 at 1:42
  • $\begingroup$ @canadianer Could just give some general things that these genes would be responsible for, or is it too broad? $\endgroup$ – CMK Mar 16 '18 at 10:14
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    $\begingroup$ "besides disorders" - it's not a complete answer, but for info it's not really helpful to think of genes as 'coding for' a disorder. Any gene that does anything useful can get broken, and when it does the severity of the consequences depends on how important its normal function is. $\endgroup$ – arboviral Mar 16 '18 at 10:19
  • $\begingroup$ Can you explain a bit more of your thinking here, and show what research you have done before asking? $\endgroup$ – arboviral Mar 16 '18 at 10:19
  • $\begingroup$ @arboviral I agree with what you have said. I phrased the question that way because I had only known that genes on the X-chromosome were responsible for certain disorders until that point. $\endgroup$ – CMK Mar 19 '18 at 3:30

Here is the list! There are about 900 protein coding genes and about 500 non-coding transcribed sequences. It is not going to be feasible to explain you the function of every single one of those genes. Your question is hence too broad.

You will find here on wikipedia a small subset of those ~900 genes.

If your question was

Are all genes that are on the X chromosome related to sex?

Then, the answer is "no". Most of them have nothing to do with gender specific traits.

  • $\begingroup$ Where did the quoted section in your answer come from? (I agree it sounds like that is the misapprehension that prompted the question, but I don't see it anywhere.) $\endgroup$ – arboviral Mar 16 '18 at 10:16
  • $\begingroup$ Thank you for your answer and for the links, although I would he lying if I said that I understood what they were saying. However, concerning the genes involved with sex determination, what do those genes determine, in fact? $\endgroup$ – CMK Mar 16 '18 at 10:47
  • $\begingroup$ I have changed "sec determination" with "gender specific trait". That was a typo. In humans, there are only one gene affecting sex determination, it is SRY (coding for TDF) present on the Y chromosome. I don't know much else about eventual gender specific beneficial genes on the X chromosome. $\endgroup$ – Remi.b Mar 16 '18 at 14:46
  • $\begingroup$ Somewhat related: Do males of all sexual species have Y chromosomes? $\endgroup$ – Remi.b Mar 16 '18 at 16:21
  • $\begingroup$ @Remi.b Thank you for your response. What is your opinion on this article, which says that there is more than one gene that affects sex determination? genderedinnovations.stanford.edu/case-studies/… $\endgroup$ – CMK Mar 19 '18 at 3:25

I would like to start the answer by mentioning that I was fortunate to attend a lecture by Jenny Graves, a scientist working on X chromosomes recently.
In her lecture she mentioned the genes on X-chromosomes as "brain and balls" genes. As Remi.b has already added a list you can go through it to find a few of these genes. I am highlighting a few of them as follows:-

  1. Androgen receptor (AR) - Required for prostrate formation in males. Mutations may lead to muscular degeneration and loss of motor control (Kennedy's syndrome).
  2. AIFM1 - An inhibitor of apoptosis. Mutations may lead to neurodegenerative conditions like Charcot-Marie-Tooth disease 4.
  3. MeCP2 - Heterozygous female MeCP2 mutants suffer from Rett Syndrome. It is almost exclusively seen in females because male mutant embryos die during pregnancy.
  4. BEX1, BEX2 and BEX4 - Brain-expressed X-linked (BEX) proteins

Also regarding sex determination - the mammalian XY sex determination is Y centered i.e. the SRY gene on the Y chromosome is the gene responsible for determining maleness. Interestingly some species not using the XY system have evolved female specific sex determination genes. I will add relevant citations when I have time.

  • $\begingroup$ I added a few relevant citations because someone downvoted without providing a reason. $\endgroup$ – Roni Saiba Mar 16 '18 at 23:42
  • $\begingroup$ Thank you for your answer. So, does this mean that the X+chromosome contains genes that direct the formation of part of the male reproductive system? $\endgroup$ – CMK Mar 19 '18 at 3:18
  • $\begingroup$ Yes. Since, the size of the Y chromosome is much smaller than X chromosome it does not contain many genes. Most of the genes on Y are only involved in early determination of sex. Information regarding organ development is still encoded by X. $\endgroup$ – Roni Saiba Mar 19 '18 at 12:37
  • $\begingroup$ @CMK Also consider upvoting if the answer satisfies your curiosity. $\endgroup$ – Roni Saiba Mar 19 '18 at 13:15
  • $\begingroup$ Thank you. I would upvote, but my reputation isn't high enough. I'm sorry about that. But, just to be clear, the X-chromosome does direct The formation of the male reproductive in part? $\endgroup$ – CMK Mar 20 '18 at 15:03

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