• Question: Why are some people colour blind?

    Asked by littlemisslaughter21 to Amy, Karen, Sarah, Will on 20 Jun 2012. This question was also asked by itsspaigee, yowitsangeline.
    • Photo: Sarah Martin

      Sarah Martin answered on 20 Jun 2012:

      Hi littlemisslaughter21,

      “Colour blind” is a misleading name – there is no actual blindness but there is a fault in the development of one or more sets of cells in the retina that perceive colour and transmit that information to the optic nerve. Colour blindness is usually a sex-linked condition. The genes that produce photopigments are carried on the X chromosome; if some of these genes are missing or damaged, color blindness will be expressed in males with a higher probability than in females because males only have one X chromosome (in females, a good gene on only one of the two X chromosomes is enough to yield the needed photopigments). So more boys are colour blind than girls!

      My brother is colour blind, but I’m not. How about you?

      🙂
      Sarah

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