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At a glance

Inherited syndrome with marfanoid features and X-linked mental retardation. It is characterized by mild-to-moderate mental retardation, marfanoid development, tall and thin stature with long and slender limbs. Other features include arachnodactyly, joint hyperextensibility, narrow face, small chin, large testes, hypotonia, and malformations of the brain and the heart. The association with an agenesis or partial development of the corpus callosum is present in more than 75% of affected individuals. The most common heart defects include spontaneous dilation of the aortic root with acute aortic valve insufficiency, dissection of the ascending aorta, and to a lesser degree ventricular and atrial septal defects.

Synonyms

X-Linked Mental Retardation with Marfanoid Habitus Syndrome; X-linked Mental Retardation with Marfanoid Habitus; Lujan Syndrome.

History

This medical condition was first described in 1984 by Jean-Pierre Fryns (b 1946), a Belgian Geneticist, and Dr J. Enrique Lujan, a pediatrician. Dr Fryns was the president of the Belgian group for the Scientific Study of Mental Deficiency.

Incidence

Approximately 59 cases reported up to 2005, almost exclusively in males. Its prevalence within the general population has not yet been determined.

Genetic inheritance

X-linked dominant transmission with a greater expressivity and penetrance in males has been suggested.

Diagnosis

Major criteria include mild-to-moderate mental retardation; marfanoid habitus; generalized hypotonia; hypernasal voice; normal secondary sexual development and normal or enlarged testicular size; characteristic craniofacial appearance with large forehead; contrasting long and narrow face; maxillary hypoplasia; long nose with high and narrow nasal bridge; short and deep philtrum; thin upper lip; and high-arched palate.

Clinical aspects

Patients appear tall and slender with long limbs and fingers (arachnodactyly). General muscular hypotonia and hyperlaxity of the joints are further features. Seizures are possible, and mental retardation is described as mild to severe. Partial or complete agenesis of the corpus callosum has been reported in some cases. A high forehead and a long, narrow face with hypoplastic mandible and micrognathia with a narrow and high-arched palate are typical. The nasal bridge is high, and the ears are low set and posteriorly rotated. Kyphoscoliosis and pectus excavatum are present in some cases. The most common heart defects include spontaneous dilation of the aortic root with acute aortic valve insufficiency, dissection of the ascending aorta, and to a lesser degree ventricular and atrial septal defects.

Precautions before anesthesia

Depending on the severity of kyphoscoliosis, restrictive lung disease, and cor pulmonale may be present. If kyphoscoliosis is significant, pulmonary investigations should include a chest radiograph, arterial blood gas analysis, and lung function tests (although they may be difficult to obtain in a mentally delayed patient). Preoperative assessment should include echocardiography to rule out congenital heart defects and to determine the size ...

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