Lyosha-Nihena syndrome

Michael Lesch, a student at the Johns Hopkins School of Medicine (USA), along with his mentor Bill Nihen, who was a pediatrician and geneticist, found signs of Lesch – Nihen syndrome accompanying hyperuricemia in two brothers 4 and 8 years old. Lesch and Nihen published the results of their research in 1964.

Hereditary metabolic disease caused by a deficiency of the enzyme hypoxanthine-phosphoribosyltransferase (EC 2.4.2.8), manifested by mental retardation, choreoathetosis, attacks of aggressive behavior with self-harm , an increased content of uric acid in the urine. The gene encoding hypoxanthine phosphoribosyl transferase is located on the X chromosome . The disease is inherited as a monogenic recessive X-linked trait. The disease is observed in males. In the first year of life, delayed psychomotor development is manifested, and later spasticity and choreoathetosis join. A characteristic sign of the disease are auto-aggressive actions that usually develop soon after the teeth erupt in children. Patients bite their lips, nails, fingers, forearms (up to self-amputation), scratch their nose and mouth, bleed themselves. Pain sensitivity remains intact. In this regard, patients often scream from the pain that they themselves have caused themselves. They can also show aggression towards other people, destroy the surrounding objects. In some cases, the condition improves when taking levodopa and the opiate antagonist naltrexone.

The diagnosis of Lyosha-Nychen syndrome is made on three main clinical elements: increased production of uric acid, neurological dysfunction, cognitive and behavioral disorders. It is quite difficult to make a diagnosis at an early stage, when these three signs are not so obvious. Suspicions may occur due to delayed development, accompanied by hyperuricemia . It is also possible the formation of kidney stones ( nephrolithiasis ) or the presence of blood in the urine ( hematuria ), caused by acid-urinary stones. Often suspicions of Lyosha-Nihena syndrome arise with the appearance of self-inflicted wounds to the patient. However, self-injurious behavior is also found in other pathological conditions, such as nonspecific mental retardation , autism , Tourette syndrome, Cornelia de Lange syndrome, Rett syndrome, Riley-Day syndrome , neurocantocytosis , hereditary neuropathies of the first type, and some psychiatric diseases. Of these, only patients with Lyosha-Nihena syndrome, de Lange syndrome and Riley-Day syndrome demonstrate tissue loss as a consequence of self-injuries. The peculiarity of Lyosha-Nihena syndrome, which distinguishes it from other syndromes related to self-inflicted wounds, is the biting of fingers, lips, inner surface of cheeks. The presence of Lyosha-Nihena syndrome should be considered only in the presence of self-traumatic behavior along with hyperuricemia and neurological dysfunction.

It is recommended the appointment of allopurinol - a synthetic analogue of hypoxanthine. There is a process of competitive inhibition of xanthine oxidase, which leads to the accumulation of hypoxanthine, but since the substance is soluble, then, compared with uric acid, it is rather quickly released from the body.