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 ba ...
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 abse ...
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 hair ...
, 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 wikt:spontaneous, spontaneous origin. From Ancient Greek, Greek ἴδιος ''idios'' "one's own" and πάθος ''pathos'' "suffering", ''idiopathy'' means approxi ...
short stature,
Léri-Weill dyschondrosteosis, and
Langer mesomelic dysplasia
Langer Mesomelic Dysplasia (LMD) is a rare congenital disorder characterized by an altered bone formation that causes a severe short and disproportionate stature.
Signs and symptoms
Clinically and radiologically, the disease is characterized by ...
.
Gene dosage Gene dosage is the number of copies of a particular gene present in a genome. Gene dosage is related to the amount of gene product (proteins or functional RNAs) the cell is able to express. Since, a gene acts as a template, the number of templates ...
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 any ...
conditions such as
triple X,
XYY
The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defin ...
,
Klinefelter,
XXYY
XXYY syndrome is a sex chromosome anomaly in which males have 2 extra chromosomes, one X chromosome, X and one Y chromosome. Human cells usually contain two sex chromosomes, one from the mother and one from the father. Usually, females have two X ...
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 sequen ...
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 ...
1 (PAR1) of the X chromosome (Xp22.33) and Y chromosome.
Since genes in PAR escape
X inactivation
X-inactivation (also called Lyonization, after English geneticist Mary Lyon) is a process by which one of the copies of the X chromosome is inactivated in therian female mammals. The inactive X chromosome is silenced by being packaged into a ...
, 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