The short-stature homeobox gene (SHOX), also known as short-stature-homeobox-containing gene, is a
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
located on both the
X and
Y chromosome
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the ...
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), commonly known as 45,X, or 45,X0,Also written as 45,XO. is a chromosomal disorder in which cells of females have only one X chromosome instead of two, or are partially missing an X chromosome (sex chromosome monosomy) lea ...
, 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.
For some medical conditions, one or more causes are somewhat understood, but in a certain percentage of people with the condition, the cause ...
short stature,
Léri-Weill dyschondrosteosis, and
Langer mesomelic dysplasia
Langer Mesomelic Dysplasia (LMD) is a rare congenital disorder characterised by altered bone formation, which typically causes affected individuals to experience shortening of the bones of the extremities as well as an abnormally short stature.
...
.
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 i ...
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 (biology), cell, for example a human somatic (biology), somatic cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more plo ...
conditions such as
triple X,
XYY
In 1931, the International Commission on Illumination (CIE) published the CIE 1931 color spaces which define the relationship between the visible spectrum and human color vision. The CIE color spaces are mathematical models that comprise a "stan ...
,
Klinefelter,
XXYY
XXYY syndrome is a sex chromosome anomaly in which males have two extra chromosomes, one 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 chromosomes ...
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 sequence ...
s and is located in the
pseudoautosomal region
The pseudoautosomal regions or PARs are Homology (biology), homologous sequences of Nucleotide, nucleotides found within the Sex chromosome, sex chromosomes of species with an XY sex-determination system, XY or ZW sex-determination system, ZW mech ...
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 F. Lyon, 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 ...
, 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 Nucleic acid sequence, DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. Mutations in a homeobox may change large-scale anatomical features of ...
gene, meaning that it helps to regulate development.
References
Further reading
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
External links
*
GeneReview/NCBI/NIH/UW entry on SHOX-Related Haploinsufficiency Disorders
__notoc__
{{DEFAULTSORT:Short Stature Homeobox Gene
Genes on human chromosome X
Genes on human chromosome Y
Homeobox genes