Midphalangeal hair

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Midphalangeal hair, or the presence/absence of hair on the middle phalanx of the ring finger, is one of the most widely studied markers in classical genetics of human populations. Although this polymorphism was observed at other fingers as well, for this kind of research, the fourth finger of the hand has been conventionally selected.

Description

In humans,

racial tendencies. Hair is present on the middle segment of the fingers more frequently than on the middle segment of the toes. Hair is most often found on the middle segment of the fourth finger
.

History

Willier (1974),

hereditary
.

Inheritance

The

recessive genes
, or of one primary recessive gene with several modifying factors that regulate the distribution of hair when it is present.' Stated conversely, 'despite the fact that in evolutionary progress hair is disappearing from the mid-digital region, its presence...may be regarded as the manifestation of a dominant trait.'

Bernstein and Burks (1942) [2] suggested that 5 allelic genes, A-0 to A-4, 'control the inheritance and distribution of middigital hair involving but a single gene substitution (the subscript denoting the number of fingers affected with middigital hair),' and that the genes for the presence of hair are dominant over the genes for its absence.[3]

From a

environmental differences make genetic analysis of the trait
difficult.

Egesi and Rashid (2010) reviewed the subject of middigital hair and its clinical significance.[4]

Population genetics

Danforth (1921) reported that middigital hair was present in men more often than in women. Caucasians were found to have a higher incidence of middle phalangeal hair than other ethnic groups, including

Afro-Americans, American Indians, and Japanese
.

Saldanha and Guinsburg (1961) studied the presence or absence of middigital hair in a white population of

Afro-Americans, the figures varied between about 10% and 40%. The trait was virtually absent among the Inuit.[5]

  • Midphalangeal hairiness (%)

[6][page needed][7][page needed]

Population Males Females Total
% % d
Arabs – Christians − Baghdad 48 64.6 14 50.7 62 0.62
Arabs – Muslims − Baghdad 233 67.4 132 50.7 265 0.73
Armenians − Beirut 165 62.4 172 61.6 337 0.62
Basques − San Sebastián 25 64.0 53 73.6 78 0.54
Bosnia and Herzegovina – 10 localities[8] 2,964 44.13 2,296 39.85 5,260 0.71
Egypt – Copts − Cairo 55 65.5 52 46.2 107 0.66
Egypt – Muslims − Cairo 228 45.6 203 36.2 431 0.67
Georgia − Tbilisi 62 56.4 71 33.8 133 0.75
Jews − Baghdad 69 71.0 136 59.6 205 0.60
Syrians – Christians − Baghdad 90 68.9 16 50.0 106 0.58
Syrians – Muslims − Baghdad 129 58.1 66 54.5 195 0.66
Ukraine − Kharkiv 58 56.9 112 50.9 170 0.69

See also

References

  1. PMID 11615640
  2. ^ Beckman L., Book J. A. (1959): Distribution and inheritance of mid-digital hair in Sweden. Hereditas 45: 215-220.
  3. PMID 18144480
  4. PMID 21122054
    .
  5. ^ Saldanha P. H., Guinsburg S. (1961): Distribution and inheritance of middle phalangeal hair in a white population of São Paulo, Brazil. Hum. Biol., 33: 237-249, Note: Erratum: Hum. Biol. 33: 384.
  6. ^ Boyd W. C. (1950): Genetics and the races of man. Little, Brown and Company, Boston.
  7. ISBN 978-05526-5390-9
    .
  8. ^ Hadžiselimović R. (1981): Genetic distance among local human populations in Bosnia and Herzegovina (Yugoslavia). Coll. Antrop., 5. (Suppl.): 63-66.
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