Structural variation in Xq28: MECP2 duplications in 1% of patients with unexplained XLMR and in 2% of male patients with severe encephalopathy

Dorien Lugtenberg, Tjitske Kleefstra, Astrid R. Oudakker, Willy M. Nillesen, Helger G. Yntema, Andreas Tzschach, Martine Raynaud, Dietz Rating, Hubert Journel, Jamel Chelly, Cyril Goizet, Didier Lacombe, Jean Michel Pedespan, Bernard Echenne, Gholamali Tariverdian, Declan O'Rourke, Mary D. King, Andrew Green, Margriet van Kogelenberg, Hilde Van EschJozef Gecz, Ben C.J. Hamel, Hans van Bokhoven, Arjan P.M. de Brouwer

Research output: Contribution to journalArticlepeer-review

102 Citations (Scopus)

Abstract

Duplications in Xq28 involving MECP2 have been described in patients with severe mental retardation, infantile hypotonia, progressive spasticity, and recurrent infections. However, it is not yet clear to what extent these and accompanying symptoms may vary. In addition, the frequency of Xq28 duplications including MECP2 has yet to be determined in patients with unexplained X-linked mental retardation and (fe)males with severe encephalopathy. In this study, we used multiplex ligation-dependent probe amplification to screen Xq28 including MECP2 for deletions and duplications in these patient cohorts. In the group of 283 patients with X-linked mental retardation, we identified three Xq28 duplications including MECP2, which suggests that approximately 1% of unexplained X-linked mental retardation may be caused by MECP2 duplications. In addition, we found three additional MECP2 duplications in 134 male patients with mental retardation and severe, mostly progressive, neurological symptoms, indicating that the mutation frequency could be as high as 2% in this group of patients. In 329 female patients, no Xq28 duplications were detected. In total, we assessed 13 male patients with a MECP2 duplication from six unrelated families. Moderate to severe mental retardation and childhood hypotonia was noted in all patients. The majority of the patients also presented with absent speech, seizures, and progressive spasticity as well as ataxia or an ataxic gait and cerebral atrophy, two previously unreported symptoms. We propose to implement DNA copy number testing for MECP2 in the current diagnostic testing in all males with moderate to severe mental retardation accompanied by (progressive) neurological symptoms.

Original languageEnglish
Pages (from-to)444-453
Number of pages10
JournalEuropean Journal of Human Genetics
Volume17
Issue number4
DOIs
Publication statusPublished - 1 Jan 2009
Externally publishedYes

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Cite this