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Why is a genetic mutation in P450scc usually lethal?
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Correct answer:
P450scc is the single mitochondrial protein that mediates all steps in the conversion of cholesterol to pregnenolone. The activity of this protein is vital to the production of steroid hormones as it represents the rate-limiting step for the entire steroid pathway. It is also the major site through which LH and FSH (tropic hormones) exert their hormonal effects on the gonads. If a genetic mutation in P450scc occurs, steroid hormone production cannot occur. This includes production of progesterone in the placenta, which is vital to maintaining pregnancy (see Chapter 19).
