Brunner syndrome

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Brunner syndrome
Other namesMonoamine oxidase A deficiency
X-linked recessive (carrier mother).svg
This condition is inherited in an X-linked recessive manner.

Brunner syndrome is a rare genetic disorder associated with a mutation in the MAOA gene. It is characterized by lower than average IQ (typically about 85), problematic impulsive behavior (such as pyromania, hypersexuality and violence), sleep disorders and mood swings. [1] [2] It was identified in fourteen males from one family in 1993. [1] [3] It has since been discovered in additional families. [4]

Contents

Signs and symptoms

The following signs and symptoms occur in people with monoamine oxidase A deficiency, which causes Brunner syndrome: [5]

Causes

Brunner syndrome is caused by a monoamine oxidase A (MAOA) deficiency, which leads to an excess of monoamines in the brain, such as serotonin, dopamine, and norepinephrine (noradrenaline). In both mice and humans, a mutation was located on the eighth exon of the MAO-A gene, which created a dysfunctional MAO-A gene. [6] [7] The regular function of MAO-A, breaking down monoamines, is disrupted, and monoamines build up within the brain. Mice that lacked a functional MAO-A gene displayed higher levels of aggression, in comparison to mice with a functional MAO-A gene. [7]

Diagnosis

No diagnostic method has been established yet.[ citation needed ]

Treatment

History

Brunner Syndrome was described in 1993 by H.G. Brunner and his colleagues upon the discovery of a particular genetic defect in male members of a large Dutch family. [6] Brunner found that all of the male family members with this defect reacted aggressively when angry, fearful, or frustrated. The defect discovered was later found to be a mutation in the gene that codes for monoamine oxidase A (MAOA gene). [6] Brunner said that an "MAO-A deficiency is associated with a recognizable behavioural phenotype that included disturbed regulation of impulsive aggression". [6]

A letter published by Hebebrand and Klug (1995) [8] criticized Brunner's findings for not using strict DSM criteria.

Society and culture

Brunner's findings have been used to argue that genetics, rather than decision-making processes, can cause criminal activity. [9] Evidence supporting the genetic defense stems from both Brunner's findings and a series of studies on mice. [10] To prove the correlation between MAO-A deficiency and aggression in courts, it is often contended that individuals cannot be held accountable for their genes, and as a result, should not be held responsible for their dispositions and resulting actions. [9] [10]

Related Research Articles

<span class="mw-page-title-main">Monoamine oxidase</span> Family of enzymes

Monoamine oxidases (MAO) are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The first such enzyme was discovered in 1928 by Mary Bernheim in the liver and was named tyramine oxidase. The MAOs belong to the protein family of flavin-containing amine oxidoreductases.

<span class="mw-page-title-main">Noonan syndrome</span> Genetic condition involving facial, heart, blood and skeletal features

Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored eyes, low-set ears, a short neck, and a small lower jaw. Heart problems may include pulmonary valve stenosis. The breast bone may either protrude or be sunken, while the spine may be abnormally curved. Intelligence is often normal. Complications of NS can include leukemia.

<span class="mw-page-title-main">Stickler syndrome</span> Genetic connective tissue disorder

Stickler syndrome is a group of rare genetic disorders affecting connective tissue, specifically collagen. Stickler syndrome is a subtype of collagenopathy, types II and XI. Stickler syndrome is characterized by distinctive facial abnormalities, ocular problems, hearing loss, and joint and skeletal problems. It was first studied and characterized by Gunnar B. Stickler in 1965.

<span class="mw-page-title-main">Haploinsufficiency</span> Concept in genetics

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 phenotype. Haploinsufficiency may arise from a de novo or inherited loss-of-function mutation in the variant allele, such that it yields little or no gene product. Although the other, standard allele still produces the standard amount of product, the total product is insufficient to produce the standard phenotype. This heterozygous genotype may result in a non- or sub-standard, deleterious, and (or) disease phenotype. Haploinsufficiency is the standard explanation for dominant deleterious alleles.

<span class="mw-page-title-main">ATP7A</span> Protein-coding gene in humans

ATP7A, also known as Menkes' protein (MNK), is a copper-transporting P-type ATPase which uses the energy arising from ATP hydrolysis to transport Cu(I) across cell membranes. The ATP7A protein is a transmembrane protein and is expressed in the intestine and all tissues except liver. In the intestine, ATP7A regulates Cu(I) absorption in the human body by transporting Cu(I) from the small intestine into the blood. In other tissues, ATP7A shuttles between the Golgi apparatus and the cell membrane to maintain proper Cu(I) concentrations in the cell and provides certain enzymes with Cu(I). The X-linked, inherited, lethal genetic disorder of the ATP7A gene causes Menkes disease, a copper deficiency resulting in early childhood death.

<span class="mw-page-title-main">Monoamine oxidase A</span> Endogenous enzyme

Monoamine oxidase A, also known as MAO-A, is an enzyme that in humans is encoded by the MAOA gene. This gene is one of two neighboring gene family members that encode mitochondrial enzymes which catalyze the oxidative deamination of amines, such as dopamine, norepinephrine, and serotonin. A mutation of this gene results in Brunner syndrome. This gene has also been associated with a variety of other psychiatric disorders, including antisocial behavior. Alternatively spliced transcript variants encoding multiple isoforms have been observed.

<span class="mw-page-title-main">Ectrodactyly–ectodermal dysplasia–cleft syndrome</span> Medical condition

Ectrodactyly–ectodermal dysplasia–cleft syndrome, or EEC, and also referred to as EEC syndrome and split hand–split foot–ectodermal dysplasia–cleft syndrome is a rare form of ectodermal dysplasia, an autosomal dominant disorder inherited as a genetic trait. EEC is characterized by the triad of ectrodactyly, ectodermal dysplasia, and facial clefts. Other features noted in association with EEC include vesicoureteral reflux, recurrent urinary tract infections, obstruction of the nasolacrimal duct, decreased pigmentation of the hair and skin, missing or abnormal teeth, enamel hypoplasia, absent punctae in the lower eyelids, photophobia, occasional cognitive impairment and kidney anomalies, and conductive hearing loss.

The field of psychology has been greatly influenced by the study of genetics. Decades of research have demonstrated that both genetic and environmental factors play a role in a variety of behaviors in humans and animals. The genetic basis of aggression, however, remains poorly understood. Aggression is a multi-dimensional concept, but it can be generally defined as behavior that inflicts pain or harm on another.

<span class="mw-page-title-main">RAPADILINO syndrome</span> Medical condition

RAPADILINO syndrome is an autosomal recessive disorder characterized by:

<span class="mw-page-title-main">Laminopathy</span> Medical condition

Laminopathies are a group of rare genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina. Since the first reports of laminopathies in the late 1990s, increased research efforts have started to uncover the vital role of nuclear envelope proteins in cell and tissue integrity in animals. Laminopathies are a group of degenerative diseases, other disorders associated with inner nuclear membrane proteins are known as nuclear envelopathies.

<span class="mw-page-title-main">OCRL</span> Protein-coding gene in the species Homo sapiens

Inositol polyphosphate 5-phosphatase OCRL-1, also known as Lowe oculocerebrorenal syndrome protein, is an enzyme encoded by the OCRL gene located on the X chromosome in humans.

<span class="mw-page-title-main">CHD7</span> Protein-coding gene in the species Homo sapiens

Chromodomain-helicase-DNA-binding protein 7 is an ATP-dependent 'chromatin' or 'nucleosome' remodeling factor that in humans is encoded by the CHD7 gene.

<span class="mw-page-title-main">Monoamine oxidase B</span> Protein-coding gene in the species Homo sapiens

Monoamine oxidase B, also known as MAO-B, is an enzyme that in humans is encoded by the MAOB gene.

<span class="mw-page-title-main">SGCG</span> Protein-coding gene in the species Homo sapiens

Gamma-sarcoglycan is a protein that in humans is encoded by the SGCG gene. The α to δ-sarcoglycans are expressed predominantly (β) or exclusively in striated muscle. A mutation in any of the sarcoglycan genes may lead to a secondary deficiency of the other sarcoglycan proteins, presumably due to destabilisation of the sarcoglycan complex. The disease-causing mutations in the α to δ genes cause disruptions within the dystrophin-associated protein (DAP) complex in the muscle cell membrane. The transmembrane components of the DAP complex link the cytoskeleton to the extracellular matrix in adult muscle fibres, and are essential for the preservation of the integrity of the muscle cell membrane.

<span class="mw-page-title-main">COX15</span> Protein-coding gene in the species Homo sapiens

Cytochrome c oxidase assembly protein COX15 homolog (COX15), also known as heme A synthase, is a protein that in humans is encoded by the COX15 gene. This protein localizes to the inner mitochondrial membrane and involved in heme A biosynthesis. COX15 is also part of a three-component mono-oxygenase that catalyses the hydroxylation of the methyl group at position eight of the protoheme molecule. Mutations in this gene has been reported in patients with hypertrophic cardiomyopathy as well as Leigh syndrome, and characterized by delayed onset of symptoms, hypotonia, feeding difficulties, failure to thrive, motor regression, and brain stem signs.

<span class="mw-page-title-main">Marshall syndrome</span> Medical condition

Marshall syndrome is a genetic disorder of the connective tissue that can cause hearing loss. The three most common areas to be affected are the eyes, which are uncommonly large, joints and the mouth and facial structures. Marshall syndrome and Stickler syndrome closely resemble each other; in fact they are so similar, some say they are the same. The condition is named for D. Weber.

A behaviour mutation is a genetic mutation that alters genes that control the way in which an organism behaves, causing their behavioural patterns to change.

<span class="mw-page-title-main">Jean-Louis Mandel</span>

Jean-Louis Mandel, born in Strasbourg on February 12, 1946, is a French medical doctor and geneticist, and heads a research team at the Institute of Genetics and Molecular and Cellular Biology (IGBMC). He has been in charge of the genetic diagnosis laboratory at the University Hospitals of Strasbourg since 1992, as well as a professor at the Collège de France since 2003.

<span class="mw-page-title-main">DiGeorge syndrome</span> Medical condition caused by chromosomal abnormality

DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is a syndrome caused by a microdeletion on the long arm of chromosome 22. While the symptoms can vary, they often include congenital heart problems, specific facial features, frequent infections, developmental disability, intellectual disability and cleft palate. Associated conditions include kidney problems, schizophrenia, hearing loss and autoimmune disorders such as rheumatoid arthritis or Graves' disease.

Xandra Owens Breakefield is an American neurologist who is a professor of neurology at the Harvard Medical School. Her research makes use of molecular genetics to understand the origins of inherited neurological diseases.

References

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