The short-stature homeobox gene (SHOX), also known as short-stature-homeobox-containing gene, is a
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
located on both the
X and
Y chromosome
The Y chromosome is one of two sex chromosomes ( allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or a ...
s, which is associated with
short stature
Short stature refers to a height of a human which is below typical. Whether a person is considered short depends on the context. Because of the lack of preciseness, there is often disagreement about the degree of shortness that should be called ' ...
in humans if mutated or present in only one copy (
haploinsufficiency
Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the wild-type allele at a locus in heterozygous combination with a variant allele is insufficient to produce the wild-type ...
).
Pathology
SHOX was first found during a search for the cause of short stature in women with
Turner syndrome
Turner syndrome (TS), also known as 45,X, or 45,X0, is a genetic condition in which a female is partially or completely missing an X chromosome. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low h ...
, where there is loss of genetic material from the X chromosome, typically by loss of one entire X chromosome.
Since its discovery, the gene has been found to play a role in
idiopathic
An idiopathic disease is any disease with an unknown cause or mechanism of apparent spontaneous origin. From Greek ἴδιος ''idios'' "one's own" and πάθος ''pathos'' "suffering", ''idiopathy'' means approximately "a disease of its own kind ...
short stature,
Léri-Weill dyschondrosteosis, and
Langer mesomelic dysplasia.
Gene dosage effects of extra copies of SHOX may be a cause of the increased stature seen in other sex chromosome
aneuploidy
Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with a ...
conditions such as
triple X,
XYY,
Klinefelter Klinefelter is a German surname, which is a variant of Kleinfelder. This is a topographic name for a person who worked a smallholding, or a locational surname for a person from one of the places called Kleinfeld in Germany.''Dictionary of American F ...
,
XXYY and similar syndromes.
Genetics and function
SHOX is composed of 6 different
exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequenc ...
s and is located in the
pseudoautosomal region
The pseudoautosomal regions, PAR1, PAR2, are homologous sequences of nucleotides on the X and Y chromosomes.
The pseudoautosomal regions get their name because any genes within them (so far at least 29 have been found for humans) are inherited j ...
1 (PAR1) of the X chromosome (Xp22.33) and Y chromosome.
Since genes in PAR escape
X inactivation, their dosage changes with sex chromosome aneuploidies such as Turner.
Similar genes are present in a variety of animals and insects.
It is a
homeobox
A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full ...
gene, meaning that it helps to regulate development.
References
Further reading
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External links
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GeneReview/NCBI/NIH/UW entry on SHOX-Related Haploinsufficiency Disorders__notoc__
{{DEFAULTSORT:Short Stature Homeobox Gene
Human genes