Colorblindness, Partial, Deutan Series

Alternative Names

  • CBD
  • Deutan Colorblindness
  • DCB
  • Deuteranopia
  • Green Colorblindness
Back to search Result
WHO-ICD-10 version:2010

Diseases of the eye and adnexa

OMIM Number

303800

Mode of Inheritance

X-linked

Gene Map Locus

Xq28

Description

Color blindness is a disorder that affects the way an individual perceives color.  The retina detects colors through cone cells.  There are three types of cones in the human eye, each containing a specific photo-pigment that is most sensitive to particular wavelengths of light, i.e. red, blue or green.  Individuals affected with deteranopia have no working green cone cells.  Green colors may appear beige.  The less severe condition of deuteranomaly is caused by abnormal green cone photo-pigment. Yellow and green appear redder in this disorder.

Deuteranopia affects males much more often than females.  Studies show the rate of incidence to be about one in ten males and only one in two hundred females.  The disorder is also more prevalent among the northern European population compared to other ethnicities.  Deuteranopia has been found to be more common than protanopia, the disorder affecting red cone cells.  While deuteranopia does not affect visual acuity, the inability to perceive colors properly may affect people’s day to day lives.  Children are particularly inconvenienced by the disorder as most educational aids in classrooms are color-coded.  Hence proper diagnosis must be a priority.  Multiple tests have been designed to diagnose the condition.  The Ishihara plate test, for example, uses colored circles which contain a collection of dots in different colors and sizes.  The dots form a shape that while clearly visible to most people, would be difficult to identify for those with color vision defects.  The Farnsworth-Munsell 100 Hue Test is another widely used analysis that measures the ability to discriminate between subtle color changes.  While there is no cure for the disorder, certain contact lenses and glasses may help users perceive colors more accurately. 

Molecular Genetics

Deuteranopia shows an X-linked pattern of inheritance.  In humans, the medium-wave-sensitive opsin-1 gene (OPN1MW) encodes the green cone pigment and the long-wave-sensitive opsin-1 gene (OPN1LW) encodes the red cone pigment.  While there is a single red pigment gene, green pigment genes vary in number among people.  The red pigment gene and multiple green pigment genes are arranged in a head-to-tail tandem array.  In individuals affected by deuteranopia or deuteranomaly, nonhomologous pairing and unequal crossing-over between these genes results in a hybrid 5-prime green--3-prime red fusion gene.  The disorder can also be a result of mutations in the OPN1MW gene; mainly missense mutations.

Epidemiology in the Arab World

View Map

Other Reports

Egypt

Maloukh et al. 2021 explored red-green color vision genes as phenotypic markers for identifying G6PD heterozygous variants. The inheritance pattern of the mediterranean G6PD variant and the color blindness phenotype were independent in three Arab families, indicating no epistatic effect between both loci. Subjects involved in the study included two Emirati families, and one Egyptian family 300908.G.9300908.G.10, & 300908.10 [See UAE]

Saudi Arabia

Osuobeni (1996) conducted a study to investigate the prevalence of congenital red-green color vision defects (CVDS) among Saudi males aged between 11 and 18 years.  Four hundred and ten subjects were screened from the central region of Saudi Arabia.  Six males failed the Ishihara test and six others failed both the Ishihara and D15 tests.  A total of 12 males were diagnosed with red-green CVD with a prevalence of 2.93%.  

Abdelmoneam (2011) reported the prevalence of colour vision defects (CVD) in Saudi women of Arab origin.  A total of 7467 women, aged 13 to 68 years, were recruited from all five regions of the country.  The subjects were all healthy and had no history of ocular disease.  Screening for CVD was carried out using the Ishihara pseudoisochromatic plate test and the D-15 test.  Individuals found to have CVD were further evaluated using the FM 100 hue test.  The author thus found 26 women with CVD.  Of these, 16 women were found to have a deutan defect.  It was noted that the prevalence of CVD in Saudi females (0.35%) was lower compared to other races.  The prevalence did not differ significantly between the different geographical regions of the country.  

United Arab Emirates

Maloukh et al. 2021 explored red-green color vision genes as phenotypic markers for identifying G6PD heterozygous variants. The inheritance pattern of the mediterranean G6PD variant and the color blindness phenotype were independent in three Arab families, indicating no epistatic effect between both loci. Subjects involved in the study included two Emirati families, and one Egyptian family 300908.G.9 & 300908.10 [See Egypt]

© CAGS 2024. All rights reserved.