genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

, rs6313 also called T102C or C102T is a gene variation—a

single nucleotide polymorphism In genetics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently larg ...

(SNP)—in the human ''

HTR2A The 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT2A receptor is a cell surface receptor, but has several intracellular locations. 5-HT is sh ...

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 ...

that codes for the 5-HT_2A

receptor Receptor may refer to: * Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...

. The SNP is a

synonymous substitution A synonymous substitution (often called a ''silent'' substitution though they are not always silent) is the evolutionary substitution of one base for another in an exon of a gene coding for a protein, such that the produced amino acid sequence ...

located in exon 1 of the gene where it is involved in coding the 34th

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...

. As 5-HT_2A is a

neuroreceptor A neurotransmitter receptor (also known as a neuroreceptor) is a membrane receptor protein that is activated by a neurotransmitter. Chemicals on the outside of the cell, such as a neurotransmitter, can bump into the cell's membrane, in which th ...

the SNP has been investigated in connection with

brain function A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

s and

neuropsychiatric disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...

s, and it is perhaps the most investigated SNP for its gene. Two other SNPs in HTR2A have also received much attention:

rs6311 In genetics, rs6311 is a gene variation—a single nucleotide polymorphism (SNP)—in the human ''HTR2A'' gene that codes for the 5-HT2A, 5-HT2A receptor (biology), receptor. 5-HT2A is a neuroreceptor, and several scientific studies have investigat ...

and His452Tyr (rs6314). The T102C polymorphism has been shown to be in complete

linkage disequilibrium In population genetics, linkage disequilibrium (LD) is the non-random association of alleles at different loci in a given population. Loci are said to be in linkage disequilibrium when the frequency of association of their different alleles is h ...

with the rs6311 (A-1438G). A less well investigated SNP of this gene is rs7997012.

Meta-analyses A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

seem to indicate that the SNP is not directly associated with

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...

, not with

Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...

, and two initial studies seem to indicate that it is not associated with

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

. There have been multiple studies of the effect of this SNP on

clozapine Clozapine is a psychiatric medication and is the first atypical antipsychotic (also called second-generation antipsychotic). It is primarily used to treat people with schizophrenia and schizoaffective disorders who have had an inadequate respo ...

treatment response in

. A meta-analysis published in 1998 found an association.

Individual studies

Many individual studies have been done to investigate possible effects of the rs6313 polymorphism on

phenotypes In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

such as

personality traits In psychology, trait theory (also called dispositional theory) is an approach to the study of human personality. Trait theorists are primarily interested in the measurement of ''traits'', which can be defined as habitual patterns of behaviour, tho ...

or disorders and their

endophenotype In genetic epidemiology, endophenotype (or intermediate phenotype) is a term used to separate behavioral symptoms into more stable phenotypes with a clear genetic connection. The concept was coined by Bernard John and Kenneth R. Lewis in a 1966 pap ...

s. The C-

allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

has been associated with higher

extraversion The traits of extraversion (also spelled extroversion Retrieved 2018-02-21.) and introversion are a central dimension in some human personality theories. The terms ''introversion'' and ''extraversion'' were introduced into psychology by Carl J ...

personality scores among

borderline personality disorder Borderline personality disorder (BPD), also known as emotionally unstable personality disorder (EUPD), is a personality disorder characterized by a long-term pattern of unstable interpersonal relationships, distorted sense of self, and strong ...

patients and the presence of visual and auditory

hallucinations A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combinatio ...

in patients with Late-onset Alzheimer's Disease. Multiple studies have found that individuals with schizophrenia who are homozygous for the C-allele tend to do worse on working memory tasks than do individuals with a T-allele. Rs6313 has also been shown to be associated with

novelty seeking In Cloninger's model of psychobiology, novelty seeking (NS) is an inherited, unlearned, temperamental bias toward novel signals from the environment. It can be measured along a spectrum from low to high (as with 3 other temperamental domains) and ...

among Italian

mood disorder A mood disorder, also known as an affective disorder, is any of a group of conditions of mental and behavioral disorder where a disturbance in the person's mood is the main underlying feature. The classification is in the ''Diagnostic and Stat ...

patients and

reward dependence Reward dependence is characterized as a tendency to respond markedly to signals of reward, particularly to verbal signals of social approval, social support, and sentiment. When reward dependence levels deviate from normal we see the rise of several ...

in a German population. The SNP may also be associated with

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...

. One study found no association between the SNP and suicidal behavior in a Chinese population, and another found no association with fibromyalgia syndrome.

References

SNPs on chromosome 13 {{genetics-stub