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From:
Subject: [DNA] Re: Myopia
Date: Wed, 30 Jan 2002 12:24:15 EST


I do not have figures on male/female inheritance of myopia. It is something I
have done a little research on. I do not have the sources for this data
completely, that is because I copied bits and peices from several places for
my own use with no plans to publish. Here are a couple of tidbits on myopia
and some include a study from which the data was taken. Perhaps you can
research the various studies to see if more data is available.

Myopia is the scientific term for nearsightedness. A common condition found
in approximately 25 percent of the adult population in the United States, it
is defined as a state of refraction in which parallel rays of light entering
the eye at rest are brought to focus in front of the retina. (Zadnik,
Satariano, Mutti, Sholtz and Adams 1994, 1323; Curtin 1985, 3)

One of the oldest arguments surrounding myopia is whether the condition
results from hereditary factors or environmental influences, such as reading
and close work, accommodation and diet. Several different methods of
inheritance for myopia have been proposed, including a recessive mode with
essentially complete penetration in homozygotes, with balanced polymorphism
responsible for the extremely high frequency found in some populations;
autosomal dominant, autosomal recessive, and mixtures of those. (Karlsson
1973, 87; Goss, Hampton and Wickham 1988, 876Ñ7)

Two particular genetic markers that seem to be particularly important in the
search for the gene that controls myopia: Rh factors and erythrocytic enzyme
acid phosphatase (ACP), whose locus site is 2p23. (Olmedo, Munoz,
Rodriguez-Cid, Carracedo, Gomez-Ulla and Salorio 1992, 198)

A family history of myopia is associated with the likelihood of children
developing myopia. For example, a greater prevalence of myopia exists among
the children of myopic parents than among the children of parents who do not
have myopia; (Zadnik, 1323) the probability of myopia in offspring of myopic
parents is up to three times higher than when neither parent is myopic.
(Yap,Wu, Liu, Lee and Wang 1993, 316) It is unknown, however, to what extent
these familial patterns are due to genetic or environmental factors.

Myopia is directly transmitted, but not as a unit, because many genes are
involved. (Francois, 196) The peaked distribution of ocular refraction is
consistent with the multipleÑgene hypothesis. (Bear 1991, 58) The precise
mode of inheritance of each component has not yet been clearly established.
It is still unknown whether individual refractive components are inherited
independently or if there is a hereditary correlation factor active.

Hope this helps rather than frustrates the search you are doing.
NancyS

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