Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoamine oxidase A and B (MAOA and MAOB) play key roles in deaminating neurotransmitters and various other biogenic amines. Patients deficient in one or both enzymes have distinct metabolic and neurologic profiles. MAOB deficient patients exhibit normal clinical characteristics and behavior, while MAOA deficient patients have borderline intellectual deficiency and impaired impulse control. Patients who lack both MAOA and MAOB have the most extreme laboratory values (urine, blood, and CSF serotonin 4-6 times normal, with elevated O-methylated amine metabolites and reduced deaminated metabolites) in addition to severe intellectual deficiency and behavioral problems. Mice lacking maoa and moab exhibit decreased proliferation of neural stem cells beginning in late gestation and persisting into adulthood. These mice show significantly increased monoamine levels, particularly serotonin, as well as anxiety-like behaviors as adults, suggesting that brain maturation in late embryonic development is adversely affected by elevated serotonin levels. We report the case of a male infant with a de novo Xp11.3 microdeletion exclusively encompassing the MAOA and MAOB genes. This newly recognized X-linked disorder is characterized by severe intellectual disability and unusual episodes of hypotonia, which resemble atonic seizures, but have no EEG correlate. A customized low dietary amine diet was implemented in an attempt to prevent the cardiovascular complications that can result from the excessive intake of these compounds. This is the second report of this deletion and the first attempt to maintain the patient's cardiovascular health through dietary manipulation. Even though a diet low in tyramine, phenylethylamine, and dopa/dopamine is necessary for long-term management, it will not rescue the abnormal monoamine profile seen in combined MAOA and MAOB deficiency. Our patient displays markedly elevated levels of serotonin in blood, serum, urine, and CSF while on this diet. Serotonin biosynthesis inhibitors like para-chlorophenylalanine and p-ethynylphenylalanine may be needed to lower serotonin levels in patients with absent monoamine oxidase enzymes.
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PMID:De novo microdeletion of Xp11.3 exclusively encompassing the monoamine oxidase A and B genes in a male infant with episodic hypotonia: a genomics approach to personalized medicine. 2236 43

Deletion of the monoamine oxidase (MAO)-A and MAO-B was detected in two male siblings and in their mother. The approximately 800-kb deletion, extending from about 43.0MB to 43.8MB, was detected by array comparative genomic hybridization analysis. The MAOA and MAOB genes were included in the deletion, but the adjacent Norrie disease gene, NDP, was not deleted. The boys had short stature, hypotonia, severe developmental delays, episodes of sudden loss of muscle tone, exiting behavior, lip-smacking and autistic features. The serotonin levels in their cerebrospinal fluid were extremely elevated. Another set of siblings with this deletion was reported previously. We propose recognition of MAOA/B deletion syndrome as a distinct disorder.
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PMID:MAOA/B deletion syndrome in male siblings with severe developmental delay and sudden loss of muscle tonus. 2341 21