Guest guest Posted February 9, 2011 Report Share Posted February 9, 2011 CMT is inheritable, but not always inherited. Inheritable means that the genetic defect can be passed by parents to their children. Inherited means that a child received the genetic defect from his/her parent(s). Not all CMT is inherited. As much as 10-20% of CMT cases are not inherited from parents, but are 'de novo' mutations. 'De novo' means 'new appearance' of the defect. Once the defective gene is present in a person, it may be passed to children. So, with 'de novo' mutations, the defect wasn't inherited, but it is inheritable! More info... http://www.ncbi.nlm.nih.gov/books/NBK1358/ Individuals with CMT may have a negative family history for many reasons, including mild subclinical expression in other family members, autosomal recessive inheritance, or a de novo (new) mutation for a dominant gene. About one third of individuals with identifiable point mutations in PMP22, GJB1, or MPZ causing the CMT hereditary neuropathy phenotype have de novo mutations, and thus present as simplex cases (i.e., a single occurrence in a family) [boerkoel et al 2002]. PMP22 duplications (which are much more common than point mutations) occur as de novo mutations in about 10%-20% of people with CMT1 [blair et al 1996, Bort et al 1997]. in So Calif (40's, CMT1a) Quote Link to comment Share on other sites More sharing options...
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