Genetic and Rare Diseases Information Center (GARD)


Other names people use for this condition
  • MRXSL
  • XLMR syndrome, Lubs type
  • Mental retardation, X-linked, Lubs type
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Lubs X-linked mental retardation syndrome
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My teenage son has been diagnosed with Lubs X-linked mental retardation.  What can you tell me about this condition?



  • What is Lubs X-linked mental retardation syndrome? (Back to Top)

  • Lubs X-linked mental retardation is a genetic condition first described in 1999 by Lubs et al. The condition  is associated with severe mental retardation, infantile hypotonia (low muscle tone), recurrent respiratory infection, absence of speech development, progressive neurological problems (such as seizures and spasticity), and mild facial abnormalities. [1]
  • Last Reviewed: 12/5/2008

  • What are the signs and symptoms of Lub X-linked mental retardation? Can the symptoms vary? (Back to Top)

  • Symptoms of Lubs X-linked mental retardation vary from patient to patient, including within the same family.  However, the symptoms that have been observed include severe mental retardation, facial hypotonia, spasticity, microcephaly, absent or limited speech, limited or absence of walking, seizures, and severe respiratory infections. [3]
  • Last Reviewed: 6/17/2008

  • What prognosis is associated with Lubs X-linked mental retardation? (Back to Top)

  • Because symptoms vary from patient to patient, prognosis also varies from person to person. Based on the few documented cases in the medical literature, death typically occurs before the age of 25 years.  However, there are cases in which patients have lived past the age of 25 years. [3]
  • Last Reviewed: 6/17/2008

  • What treatment is available for Lubs X-linked mental retardation? (Back to Top)

  • Treatment is individually tailored and is based on the patient's symptoms. 
  • Last Reviewed: 6/17/2008

  • What causes Lub X-linked mental retardation? (Back to Top)

  • Lub X-linked mental retardation is caused by microduplications (very small duplication) of chromosome X at Xq28.  The microduplication  consistently includes the MECP2 gene and occasionally encompasses the L1CAM gene. The MECP2 gene has been implicated in a number of other conditions including Rett syndrome. [2]
  • Last Reviewed: 6/17/2008

  • How is Lubs X-linked mental retardation inherited? (Back to Top)

  • Lubs X-linked mental retardation is inherited in an X-linked fashion, specifically in a X-linked recessive manner.
  • Last Reviewed: 6/17/2008


References  (Back)
  1. Friez MJ, Jones JR, Clarkson K, Lubs H, Abuelo D, Blaymore Bier J, et al. . Pediatrics. 6 December 2006;:. Available at: http://pediatrics.aappublications.org/cgi/content/full/118/6/e1687. June 16, 2008.
  2. MECP2 - methyl CpG binding protein 2. Genetics Home Reference. June 6, 2008 Available at: http://ghr.nlm.nih.gov/gene=mecp2. Accessed June 16, 2008.
  3. Van Esch H, Bauters M, Igantius J, Jansen M, Raynaud M, Hollanders K et al. Duplication of the MECP2 Region Is a Frequent Cause of Severe Mental Retardation and Progressive Neurological Symptoms in Males. Am. J. Hum. Genet. 2005.

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