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Archiver > GENEALOGY-DNA > 2002-01 > 1010866930


From: (Ellen Keyne Seebacher)
Subject: Re: [DNA] Re: Melungeons
Date: Sat, 12 Jan 2002 15:22:14 -0500 (EST)
In-Reply-To: <b4.4d0b9bb.2971da8d@aol.com>


Nancy quotes Allan:
>>Yet they have no special physiological characteristics or medical
>>problems other than they fit the classification of "caucasian" (they
>>were all originally English Puritans)

and adds:

> The family originally English Puritans, may have been 'mutts' as
> noted :-) but for the most part they did not include a variety of
> folks who had the previous specialization to have the physiological
> characteristics and the diseases, therefore they didn't in spite of
> isolation.

Bingo. For contrast, note the situation on Martha's Vineyard in the
18th and 19th centuries: a small group of English settlers interbred
for two centuries, which brought some recessive genes to the fore --
the most obvious of which was hereditary deafness. (By the mid-1850s,
the rate was 37 times as high as that on the mainland; in one area of
the Vineyard, one in four newborns was deaf.)

Nora Ellen Groce, who wrote the 1985 study _Everyone Here Spoke Sign
Language: Hereditary Deafness on Martha's Vineyard_, found that many
of the early settlers had come from a hilly section of Kent where the
hereditary deafness gene apparently originated. The descendants of
emigrants to the Massachusetts Bay Colony intermarried with a fairly
large population, so two recessives rarely met up; those who settled
on the Vineyard, however, had a much smaller breeding pool. It wasn't
until many of the Vineyard's deaf students went off-island to school
(and there found mates), late in the 19th century, that the genetic
isolation ended.

Folks interested in the genetics of autosomal recessive deafness
should see the OMIM database, entry #220700:

http://www.ncbi.nlm.nih.gov:80/entrez/dispomim.cgi?id=220700

--
Ellen Keyne Seebacher


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