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Genes, Surnames and Toes
By Lydia Prentiss Polydactyly generally can express itself in the form of either extra toes of fingers in the same family, although the type of polydactyly is generally constant.
When the extra didgits are on the outside (little fingers or toes) it is refered to as post-axil polydactyly. This is one of the most common conditions and, in addition, the type is most likely to be inherited without an accompanying syndrome. Pre-axil Polydactyly refers to polydactyly of the thumb or big toe - this is rare. There is also polydactyly of the middle digits which is also rare.
As polydactyly is said to be not passed on in terms of simple Mendelian inheritance, we say that it is multifactorial. More than one gene and/or other factors contribute to the display of the gene (Like diabetes). There has been mention that in some spellings of the Prentice, Prentis and Prentiss surname, the degree of extra digits varied in number. This has been known to happen, and one researcher suggested that this could be due to the number of + Polydactyly genes present. Additionally, postaxial polydactyly is further classified according to the degree of formation of the duplicated digit.
A fully formed digit is known as type A, while a fleshy appendage with or without a nail is known as type B this is also known as a pendunculated postminimi. It has been suggested that type A is the result of a full genetic load for that trait, and type B represents fewer + alleles and/or factors.
It would be of great interest to know whether the branches in the family with more toes also had more fully developed ones. At least one or more have one fully developed extra toe, and one pendunculated postminimi. Another family contains a member who was completly type B with no bones at all.
It has been debated as to whether polydactyly can be "bred out" of a population. As reported in an isolated french villiage in the nineteenth century which then became more accessable. It is this writer's opinion that it comes down to whether one believes it is due to one dominant gene with other non-genetic factors affecting penetrance (its expression), or a specific combination of genes that may be separated over time.
We would like to know more about polydactyly in other relatives, to see if it is possible that some braches "lost" some of the genes affecting the severity of the affliction.
In a future article we will address the problem whether the gene-surname-toe relationships existed prior to the various families' immigration to America.
If your Prentiss line has any of the conditions described in this article, and would be willing to share their information on a strictly confidential basis, we would enjoy hearing from you. You may contact us at prentiss@purchase.edu.
A bibliography is available on request.
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