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Getting to know Blue Cone Monochromacy

Blue Cone Monochromacy (BCM), is a rare retinal disease apparent from birth. It is often misdiagnosed, or not diagnosed for many years, perhaps decades, of the patients’ life. Our purpose is to raise awareness of the condition in the hope that it supports early diagnosis.

BCM at a glance

Blue Cone Monochromacy is a rare genetic X-linked retinal disorder. Commonly affected males show symptoms since soon after birth, while females carriers only rarely show some of the symptoms in a mild form. BCM is a stable disease, affecting an individual for his whole life.

Symptoms of BCM

  • Poor visual acuity ranging from 20/60 to 20/200 or greater, in some cases legal blindness.
  • Poor or no color discrimination, BCM individuals have only rods photoreceptors and blue cones photoreceptors. They lack the photopigments in the red (L) and the green (M) cones.
  • Hemeralopia, BCM individuals have severe diffculty coping with glare because only blue cones and rods are available to function in bright light. The severity of the symptoms, commonly know as photophobia, varies by the integrity of remaining blue cone cells.
  • Nystagmus: Nystagmus is usually present from about 3-6 months of age. It is usually, but not always, pendular and may decrease with age.
  • Myopia or high myopia
  • X-linked inheritance family pedigree. Mutations causing BCM are located in the X chromosome in the following genes and supporting components: OPN1LW, OPN1MW and the upstream LCR (Locus Control Region). Deletion in the LCR or a point mutation C203R on a single L-M opsin gene are most common forms.

So if you see a 6 month old boy with nystagmus and the parents speak about another male in their family (on the mother’s side) with similar eye problems, please consider a diagnosis of BCM.

For confirmatory diagnosis, please conduct genetic testing and participate in the research supported by BCM Families Foundation at:

University of Tuebingen – Molecular Genetics Laboratory - Germany
Contact: Susanne Kohl, MSc, PhD
Email: susanne.kohl[at]uni-tuebingen.de

Another laboratory that offers the BCM DNA test is:

Casey Eye Institute Molecular Diagnostic Laboratory Oregon Health & Science University
Contact:Director: John (Pei-Wen) Chiang, PhD,
Email: ceidiagnostics[at]ohsu.edu

For more information about the disesase, we invite you to visit the Online Mendelian Inheritance in Man (OMIM) page for BCM (omim.org/entry/303700) and our website (www.bcmfamilies.org)

BCM Families Foundation is an international non-profit organization, created in USA by families affected by BCM. Today more than 220 people worldwide are in contact with us.

We help our families with diagnosis and DNA test, and we update patients about new therapies, as for example gene therapy.  BCM Families Foundation is recognized as a non-profit organization by the USA Internal Revenue Service. Tax Identification Number 47-132773.

If you require any further information please do not hesitate to contact us:

BCM Families Foundation
Email: info[at]BCMfamilies.org
PO Box 7711 Jupiter, FL 33468-7711 USA
www.bcmfamilies.org

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