I am confused by the terminology of autosomal dominant disease, e.g.autosomal dominant polycystic kidney disease (ADPKD). As an autosomal dominant disorder, we would expect that a single mutant copy of the gene (PKD) would be enough to cause the disease. However, a heterozygote PKD gene acquired during pregnancy would not demonstrate the symptom or signs of ADPKD. Rather, a somatic mutant resulting to a homozygous PKD mutant is essential for the occurrence of the disease, which is the so-called 'double hit' hypothesis. I just can not understand why there must be 'double hit' for an autosomal dominant disorder. If homozygous mutant is essential, what is the difference between an autosomal dominant disorder and an autosomal recessive disorder? If you have some explanation to this question, please share with me. Thanks!
How are you? Polycystic kidney disease is a hereditary disorder of renal cyst formation that leads to gradual enlargement of both kidneys. Inheritance of polycystic kidney disease (PKD) is autosomal dominant or recessive (rarely). Autosomal dominant polycystic kidney disease (ADPKD) accounts for about 5% of patients with end-stage renal disease requiring replacement therapy. If a disease is autosomal dominant, it means you only need to get the abnormal gene from one parent in order for you to inherit the disease. One of the parents may often have the disease.This means that an abnormal gene from one parent is capable of causing disease, even though the matching gene from the other parent is normal. The abnormal gene "dominates" the pair of genes. If just one parent has a dominant gene defect, each child has a 50% chance of inheriting the disorder and only 25 % chance of recessive gene. I hope this helps.Take care and regards.
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