[MIM 300 615]

(Brunner syndrome))

Rare, probably often unrecognized. X-linked recessive transmission of a mutation or deletion of the MAOA and / or MAOB gene ( Xp11.3). These two genes are neighbors and 70 % similar. These enzymes are located in the outer membrane of the mitochondria of many cells, including neurons and ganglionic cells. More specifically: MAOA: liver, endothelium of the pulmonary vessels, digestive tract; MAOB: chromaffin cells, platelets. Those enzymes are flavoproteins responsible for the oxidative deamination of the monoamines:

• A: serotonin, melatonin, norepinephrine
• B: phenethylamine, benzylamine
• A and B: dopamine, tyramine, tryptamine

Clinical presentation:

-        variable intellectual deficit

-        epilepsy

-        stereotyped movements: clapping hands, snapping of lips

-        autistic traits

-        sleep disturbances

-        sometimes: impulsive aggressivity, antisocial and violent behavior (Brunner syndrome)

-        sometimes: cutaneous flush and diarrhea after ingestion of foods rich in tyramine (cheese)

Treatment: precautions identical to those indicated in patients under MAOA inhibitors therapy. Some patients show a paradoxical improvement in behavior under serotonin reuptake inhibitor therapy.

Anesthetic implications: 

hemodynamic monitoring (risk of hypertensive crisis, reflex bradycardia); in principle, one should avoid anything that can increase the level of circulating catecholamines:

• stress (deep analgesia)
• droperidol ?
• local anaesthetic solutions with adrenaline ?
• tramadol ?

In animal models (deficient in MAOA and B mouse): under general anesthesia, the blood pressure is low and the response to phenylephrine is decreased

References:

-         Hoshijima H, Takeuchi R, Kikuci K, Mizuta K.
Anesthetic management in MAO-A and MAO-B deficiency: a case report.
J Anesth 2020; 34:773-6.

Updated: October 2020