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health advisory Hospital Doctor Yu 2007-11-8 19:08:30

Answers:

Duchenne's muscular dystrophy (a common form of the disease) is an x-linked recessive trait. This means that if a boy gets a copy of this gene from his mother, he will have the disease. If a girl gets this gene from her mother, she will be a carrier, because she will also have a normal x-chromosome from her father. Here's where I start speculating. For a long complicated reason called mosiacism, a woman may get muscular dystrophy even with one normal x. I suspect that this normal x is helping to slow the diease.

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Muscular dystrophy is the term used to describe a group of inherited disorders that cause progressive muscle weakness. There are nine types of muscular dystrophies,

Myotubular, or centronuclear, myopathy belongs to the family of congenital myopathies which are characterised by muscle weakness.

Manifesting carriers of myotubular myopathy are very rare. As mentioned earlier, every female has two copies of the X chromosome. In every cell, one copy is 鈥渟witched off鈥? Usually this is random, but in some exceptional cases, more copies of the 鈥済ood鈥?chromosome are inactivated. In such cases a female may show signs of the condition, but this is likely to be only mild weakness.

VR

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Certain types of MD are sex linked traits, carried on the X chromosome. A male is XY whereas a female is XX. If the male inherits an MD-X, hes got MD. If a female inherits it, she is heterozygous and the symptoms are mild if they show at all.

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