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:: Genetics (1) :: January 18, 2007

Posted by Minci 先生 in Medical School.
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Part of the task in our genetic lecture yesterday was to come up with examples of conditions for every type of hereditary mode.

  1. X-linked recessive – Dystropinopathy (Becker’s, Duchenne), Hemophilia (A, B), Fragile X syndrome and G6PD.
  2. Aneuploidy – Klinefelter’s, Down’s, Turner’s, Edward’s syndrome.
  3. Autosomal dominance – Neurofibromatosis, Marfan, Achondroplasia, Tuberous Sclerosis.
  4. Multifactorial disorder – Neural tube defect, pyloric stenosis, cleft lip and palate, congenital dislocation of the hip.
  5. Autosomal recessive – Cystic fibrosis, Thalassemia, Sickle Cell Anaemia, Albinism.

X-linked recessive. [hope I explain this right]

The chromosomal picture in our body are made up of a pair of sex chromosomes which is XX for girls and XY for boys. The other 22 pairs are chromosomes that ‘make us up’. They will determine what colours our eyes are, inherent height etc.

A dominant mutation means that you only need that part of the gene from one parent in order for a particular condition to manifest in the child whereas for a recessive one, you’d need a part each from each parent for the condition to show.

X-linked recessive means that the defect gene is located on the sex chromosome, X. Therefore when a baby boy which has already got the Y chromosome from his father and the defected X chromosome from the mother would get the condition. There is also a chance that he’ll be normal if he gets the normal X chromosome from his mother.

A baby girl on the other hand could have the risk of being a carrier for the condition or being perfectly normal. I, for instance have a 50% risk of carrying the G6PD gene since I have an affected family member. My brother.

G6PD or glucose-6-phosphate dehydrogenase deficiency results in the person having a breakdown in their red blood cells whenever exposed  to oxidants such as infections or certain type of drugs. I have heard of extreme case scenarios where a boy ate something which contained  fava beans (kidney beans) who suffered from a very acute symptomatic attack and died. He was practically bleeding from every single orifice. How true? I have no idea.

It got my family worried for sure. My brother is 9 years younger than I am and when he was born I could practically understand certain things that the family have to be careful about. The doctor presented my parents with a list of food and drugs that might precipitate a hemolytic reaction in his body. Once the triggers were identified, my brother was basically living like any other normal human being. This condition does not affect the immune system/ heart condition/ respiratory problems etc. Well, not in my brother anyway.

Still, my father banned certain food in the house. Not only kidney beans per se, but also muruku/ ais kacang which has them in it, nut-related products except for the guaranteed safe ground nuts cap tangan, Twisties ( my bro had an allergic reaction to it).. I think that’s about it. Consequently, I disliked having nuts in my food too. Haha..

My brother was not allowed to apply to any boarding schools for safety reasons. We were worried that if he were to settle in an all boys school, there is always a chance he’ll be bullied by idiots and we don’t fancy the idea of him say,  having forced to eat a whole packet of nut biscuit etc.

My brother is 15 now and has grown wonderfully as a young man without any complications. G6PD is not something anyone should be too worried about. With the proper support for the whole family, a G6PD child can be no different from a normal child.

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Comments»

1. Puteri Nad :-( - January 18, 2007

owh benar, 2 of my anak sedara had g6pd..diorang x leh makan kacang parang ataopun horse nut kot nama omputehnye..ke horse shoe nut.. but then bila da besar they can differentiate what to eat n what not..

2. LaDy FaNtAgHiRo - January 18, 2007

owh i see…

3. little healer - January 18, 2007

yea.. i see too


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