Friday, 29 July 2011

History of Medical genetics II

The 17th-century English Physician Kenelm Digby noted the presence of the double thumb in a n Algerian Muslim family, a trait that reportedly occured in five generations and was confined to females, although Digby personally observed only mother and daughter.

The earliest definitive example, however, was that published by Pierre Louis de Maupertius (whose more theoretical contributions are noted later). In 1753, he described a German family (the proband was a Berlin surgeon named Ruhe) in whom extra digits were inherited through four generations. Maupertius specifically nored that traits was trasmitted equally by father and mother.

He also estimate that if polydactyly had a frequency of 1 in 20000 in the general population, the likelihood of its appearing by chance in three subsequent generations is 1 in 8 trillion. However, his estimate should not be taken as precise, because his ascertainment of polydactyly undoubtedly depended on the occurence of multiple cases- although, whatever allownace one makes for this, there is still a convincing departure from chance!

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