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Red hair, also known as ginger hair, is a human hair color found in 2–6% of people of Northern or Northwestern European ancestry and lesser frequency in other populations. It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the MC1R protein.
Autosomal dominant A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
The hair color of these children depends on how these alleles work together. If one allele dominates the instructions from another, it is called the dominant allele, and the allele that is overridden is called the recessive allele. In the case of a daughter with alleles for both red and brown hair, brown is dominant and she ends up with brown ...
The Fischer–Saller scale, named after Eugen Fischer and Karl Saller is used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations: A (very light blond), B to E (light blond), F to L (), M to O (dark blond), P to T (light brown to brown), U to Y (dark brown to black) and Roman numerals I to IV and V to VI (red-blond).
Mendelian traits behave according to the model of monogenic or simple gene inheritance in which one gene corresponds to one trait. Discrete traits (as opposed to continuously varying traits such as height) with simple Mendelian inheritance patterns are relatively rare in nature, and many of the clearest examples in humans cause disorders.
The letters B and b represent alleles for colour and the pictures show the resultant flowers. The diagram shows the cross between two heterozygous parents where B represents the dominant allele (purple) and b represents the recessive allele (white). Traits that are determined exclusively by genotype are typically inherited in a Mendelian pattern.
[52] [53] The differences in color are mainly caused by higher levels of melanin in the skin, hair and eyes in males. [54] [55] In one study, almost twice as many females as males had red or auburn hair. A higher proportion of females were also found to have blond hair, whereas males were more likely to have black or dark brown hair. [56]
Blond hair is controlled by an allele that is recessive to most alleles responsible for darker hair, [1] but it is not a disappearing gene.. The "disappearing blonde gene" refers to a hoax that emerged in parts of the Western world in the early 2000s, claiming that a scientific study had estimated that blonds would become extinct within the next two centuries.