WordNet

concerning characteristics that are determined by genes carried on the sex chromosomes (on the X chromosome in particular)
relating to genes or characteristics or conditions carried on the X chromosome; "an X-linked mutation"
any disease or abnormality that is determined by the sex hormones; "hemophilia is determined by a gene defect on an X chromosome"
the means of connection between things linked in series (同)nexus
a unit of length equal to 1/100 of a chain
an interconnecting circuit between two or more locations for the purpose of transmitting and receiving data (同)data link
a fastener that serves to join or connect; "the walls are held together with metal links placed in the wet mortar during construction" (同)linkup, tie, tie-in
(computing) an instruction that connects one part of a program or an element on a list to another program or list
tell the sex (of young chickens)
the properties that distinguish organisms on the basis of their reproductive roles; "she didnt want to know the sex of the foetus" (同)gender, sexuality
all of the feelings resulting from the urge to gratify sexual impulses; "he wanted a better sex life"; "the film contained no sex or violence" (同)sexual urge
either of the two categories (male or female) into which most organisms are divided; "the war between the sexes"
having sexual differentiation
characterized by sexuality; "highly sexed"

PrepTutorEJDIC

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たいまつ
〈U〉〈C〉『性』,性別 / 《the~》《形容詞を伴い集合的に》『男性』,『女性』 / 〈U〉(男女(雌雄)間の)相違[の意識] / 〈U〉性に関する事柄(情報) / 〈U〉性交 / 〈ひよこなど〉‘の'性別を見分ける

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/12/20 20:27:46」(JST)

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Experimental cross performed by Thomas Troy, illustrating the X-linked inheritance of white-eyed mutation in fruit flies.^[1]

Sex linkage is the phenotypic expression of an allele related to the allosome (sex chromosome) of the individual. In autosomal chromosomes both sexes have the same probability of existing (see Fisher's principle), but since humans have many more genes on the female X chromosome than on the male Y chromosome, these are much more common than Y-linked traits.

In mammals, the female is homogametic, with two X chromosomes (XX), while the male is the heterogametic sex, with one X and one Y chromosome (XY). Genes on the X or Y chromosome are called sex-linked. In ZW sex-determination system used by birds the opposite is true: the male is the homogametic sex (ZZ), and the female is heterogametic (ZW).

X-linked recessive traits are expressed in all heterogametics, but are only expressed in those homogametics that are homozygous for the recessive allele. For example, an X-linked recessive allele in humans causes haemophilia, which is much more common in males than females because they are hemizygous (see zygosity) and therefore express the trait when they inherit one mutant allele. In contrast, a female must inherit two mutant alleles, a less frequent event since the mutant allele is rare in the population.

The incidence of recessive X-linked phenotypes in females is the square of that in males (squaring a proportion less than one gives an outcome closer to 0 than the original). If 1 in 20 males in a human population are red-green color blind, then 1 in 400 females in the population are expected to be color-blind (¹/₂₀)*(¹/₂₀). (The term 'color-blind' is not completely accurate. There are degrees of weakness in color vision and it is now called 'color vision deficiency'.)

X-linked traits are maternally inherited from carrier mothers or from an affected father. Each son born to a carrier mother has a 50% probability of inheriting the X-chromosome carrying the mutant allele. There are a few Y-linked traits; these are inherited from father.

In classical genetics, a reciprocal cross is performed to test if a trait is sex-linked.

(A)

(B)

(C)

Illustration of some X-linked heredity outcomes (A) the affected father has one X-linked dominant allele, the mother is homozygous for the recessive allele: only daughters (all) will be affected. (B) the affected mother is heterozygous with one copy of the X-linked dominant allele: both daughters and sons will have 50% probability to be affected. (C) the heterozygous mother is called "carrier" because she has one copy of the recessive allele: sons will have 50% probability to be affected, 50% of unaffected daughters will become carriers like their mother.^[2]

X-linked dominant inheritance

An example pedigree chart of the inheritance of a sex linked disorder.

Each child of a mother affected with an X-linked dominant trait has a 50% chance of inheriting the mutation and thus being affected with the disorder. If only the father is affected, 100% of the daughters will be affected, since they inherit their father's X-chromosome, and 0% of the sons will be affected, since they inherit their father's Y-chromosome.

Examples

Alport's syndrome
Aarskog-Scott syndrome
Coffin–Lowry syndrome (CLS)
idiopathic hypoparathyroidism
incontinentia pigmenti
Ornithine carbamoyltransferase deficiency
Rett syndrome (RS)
vitamin D resistant rickets (XLH)
fragile X syndrome

X-linked recessive inheritance

Females possessing one X-linked recessive mutation are considered carriers and will generally not manifest clinical symptoms of the disorder. All males possessing an X-linked recessive mutation will be affected, since males have only a single X-chromosome and therefore have only one copy of X-linked genes. All offspring of a carrier female have a 25% chance of inheriting the mutation if the father does not carry the recessive allele. All female children of an affected father will be carriers (assuming the mother is not affected or a carrier), as daughters possess their father's X-chromosome. If the mother is not a carrier, no male children of an affected father will be affected, as males only inherit their father's Y-chromosome.

Examples

ALD
Duchenne muscular dystrophy
Hunter syndrome
Menkes disease (kinky hair syndrome)
Glucose-6-phosphate dehydrogenase deficiency
Haemophilia A and B
Fabry's disease
Wiskott-Aldrich syndrome
Bruton's agammaglobulinemia
Color blindness
Complete androgen insensitivity syndrome
Congenital aqueductal stenosis (hydrocephalus)
Inherited nephrogenic diabetes insipidus

Y-linked

VAJ

Various failures in the SRY genes

Sex-linked traits in other animals

White eyes in Drosophila melanogaster flies— the first sex-linked gene discovered.^[3]
Fur color in domestic cats: the gene that causes orange pigment is on the X chromosome; thus a Calico or tortoiseshell cat, with both black (or gray) and orange pigment, is nearly always female.
The first sex-linked gene ever discovered was the "lacticolor" X-linked recessive gene in the moth Abraxas grossulariata by Leonard Doncaster.^[4]

Related terms

It is important to distinguish between sex-linked characters, which are controlled by genes on sex chromosomes, and two other categories.^[5]

Sex-influenced traits

Sex-influenced or sex-conditioned traits are phenotypes affected by whether they appear in a male or female body.^[6] Even in a homozygous dominant or recessive female the condition may not be expressed fully. Example: baldness in humans.

Sex-limited traits

These are characters only expressed in one sex. They may be caused by genes on either autosomal or sex chromosomes.^[6] Examples: female sterility in Drosophila; and many polymorphic characters in insects, especially in relation to mimicry. Closely linked genes on autosomes called "supergenes" are often responsible for the latter.^[7]^[8]^[9]

References

^ Morgan, Thomas Troy 1919. The physical basis of heredity. Philadelphia: J.B. Lippincott Company.
^ Genetics home reference (2006), genetic conditions illustrations, National Library of Medicine.
^ Morgan T.H. 1910. Sex-limited inheritance in Drosophila. Science 32: 120-122
^ Doncaster L. & Raynor G.H. 1906. Breeding experiments with Lepidoptera. Proceedings of the Zoological Society of London. 1: 125-133
^ Zirkle, Conrad 1946. The discovery of sex-influenced, sex limited and sex-linked heredity. In Ashley Montagu M.F. (ed) Studies in the history of science and learning offered in homage to George Sarton on the occasion of his sixtieth birthday. New York: Schuman, p167–194.
^ ^a ^b King R.C; Stansfield W.D. & Mulligan P.K. 2006. A dictionary of genetics. 7th ed, Oxford University Press. ISBN 0-19-530761-5
^ Mallet J.; Joron M. (1999). "The evolution of diversity in warning color and mimicry: polymorphisms, shifting balance, and speciation". Annual Review of Ecology and Systematics. 30: 201–33. doi:10.1146/annurev.ecolsys.30.1.201.
^ Ford E.B. 1965. Genetic polymorphism. p17-25. MIT Press 1965.
^ Joron M, Papa R, Beltrán M, et al. (2006). "A conserved supergene locus controls colour pattern diversity in Heliconius butterflies". PLoS Biol. 4 (10): e303. doi:10.1371/journal.pbio.0040303. PMC 1570757 . PMID 17002517.

UpToDate Contents

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1. 着床前の男女生み分け技術 techniques for preimplantation sex selection
2. 思春期の性 adolescent sexuality
3. メンデル遺伝の概要 overview of mendelian inheritance
4. 性行為に伴う一次性頭痛 primary headache associated with sexual activity
5. 貧血を有する小児に対するアプローチ approach to the child with anemia

English Journal

Y-linked Mendelian inheritance of giant and dwarf male morphs in shell-brooding cichlids.

Wirtz Ocana S1, Meidl P2, Bonfils D1, Taborsky M3.
Proceedings. Biological sciences / The Royal Society.Proc Biol Sci.2014 Nov 7;281(1794). pii: 20140253. doi: 10.1098/rspb.2014.0253.
Behavioural variation among conspecifics is typically contingent on individual state or environmental conditions. Sex-specific genetic polymorphisms are enigmatic because they lack conditionality, and genes causing adaptive trait variation in one sex may reduce Darwinian fitness in the other. One wa
PMID 25232141

Gender-specific neuroanatomical basis of behavioral inhibition/approach systems (BIS/BAS) in a large sample of young adults: A voxel-based morphometric investigation.

Li Y1, Qiao L1, Sun J1, Wei D1, Li W1, Qiu J1, Zhang Q2, Shi H3.
Behavioural brain research.Behav Brain Res.2014 Nov 1;274:400-8. doi: 10.1016/j.bbr.2014.08.041. Epub 2014 Aug 27.
The behavioral inhibition system (BIS) and the behavioral activation system (BAS) are two fundamental motivational systems which are not only responsible for affective states, behavior and personality, but also related to predispositions for various forms of psychopathology. A wide range of previous
PMID 25172180

Genetic and pharmacological modulation of the steroid sulfatase axis improves response control; comparison with drugs used in ADHD.

Davies W1, Humby T1, Trent S1, Eddy JB2, Ojarikre OA3, Wilkinson LS1.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology.Neuropsychopharmacology.2014 Oct;39(11):2622-32. doi: 10.1038/npp.2014.115. Epub 2014 May 20.
Maladaptive response control is a feature of many neuropsychiatric conditions, including attention deficit hyperactivity disorder (ADHD). As ADHD is more commonly diagnosed in males than females, a pathogenic role for sex-linked genes has been suggested. Deletion or point mutation of the X-linked ST
PMID 24842408