The Inheritance of Retinal Degenerations
Note: This document was written by Jill Hennessey and Janet
Glover-Kerkvliet and graphics created by Tim Phelps.
Information contained on these
web pages is ©1995
Foundation Fighting Blindness and is available from them in
written, audio and braille form.
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You or a relative have a retinal degenerative disease like retinitis
pigmentosa (RP) or macular degeneration. Understandably you are
concerned about the severity of the disease and the possible loss of
sight. In addition the ophthalmologist has said that is an inherited
disease and that there is a risk that other family members may be
affected. Now is the time to consult with an ophthalmologist trained
in genetics with medical geneticist or with a genetic counselor.
Only after a thorough review of your family history can the risk
for other family members be assessed.
The information found in this web page cannot replace genetic
counseling; Genetic counseling is provided only by trained
professionals in a medical setting. Rather, you can use this
web page to help prepare for the counseling session and you
can refer to it after counseling to help you remember what was
Retinitis pigmentosa (RP) is the name given to a group of retinal
degenerative disease characterized by a breakdown of the retina
the thin layers of light-sensing cells in the back of the eye
(Figure 1). The first symptom of RP is usually night blindness
follow by reduction in peripheral vision which leads to tunnel
Figure 1. Diagram of an eye. The retina forms the
inner back layer.
Macular degeneration describes a group of retinal degenerative
diseases that is characterized by a breakdown of the macuIa,
the small center portion of the retina. The macula provides the
sharp central vision needed for reading small print and for
recognizing faces at a distance. Symptoms of macular degeneration
may include seeing dark or empty areas in the center of
vision, and seeing distortions of lines and shapes in every day
Other retinal degenerative diseases affect specific layers of the
retina and may also involve other parts of the body. Retinal
degenerative diseases are also referred to as retinal degenerations.
Although usually diagnosed in young adulthood, certain forms of
retinal degenerations are evident in early childhood, and other
forms may not appear until the fifth or sixth decade of life.
Because most retinal degenerations are inherited, they can occur
in more than one individual in a family. In some families, the
disease affects both parent and child. In other families, unaffected
parents have one or more children with a retinal degeneration.
To understand how retinal degenerations are inherited, it is
important to first review the basic facts about genetics, the
science of heredity.
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Date last modified December 4, 1998