Altered carbon dioxide metabolism and creatine abnormalities in rett syndrome

Nicky S J Halbach, Eric E J Smeets, Jörgen Bierau, Irene M L W Keularts, Guy Plasqui, Peter O O Julu, Ingegerd Witt Engerström, Jaap A. Bakker, Leopold M G Curfs

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Despite their good appetite, many females with Rett syndrome (RTT) meet the criteria for moderate to severe malnutrition. Although feeding difficulties may play a part in this, other constitutional factors such as altered metabolic processes are suspected. Irregular breathing is a common clinical feature, leading to chronic respiratory alkalosis or acidosis. We assumed that these changes in intracellular pH cause disturbances in the metabolic equilibrium, with important nutritional consequences. The study population consisted of a group of thirteen well-defined RTT girls with extended clinical, molecular and neurophysiological assessments. Despite normal levels of total dietary energy and protein intakes, malnutrition was confirmed based on significantly low fat-free mass index (FFMI) values. Biochemical screening of multiple metabolic pathways showed significantly elevated plasma creatine concentrations and increased urinary creatine/creatinine ratio in five RTT girls. Four girls, 10 years and older, were forceful breathers, one 13-year-old girl had an undetermined cardiorespiratory phenotype. An isolated increase of the urinary creatine/creatinine ratio was seen in two girls, a 9-year old forceful and a 4-year old feeble breather. Given that the young girls are feeble breathers and the older girls are forceful breathers, it is impossible to determine whether the elevated creatine concentrations are due to increasing age or cardiorespiratory phenotype. Furthermore, MeCP2 deficiency may cause epigenetic aberrations affecting the expression of the creatine-transporter gene, which is located at Xq28. Further studies are required to confirm these findings and to provide greater insight into the pathogenesis of the abnormal creatine metabolism in RTT.

Original languageEnglish
Pages (from-to)117-24
Number of pages8
JournalJIMD reports
Volume3
DOIs
Publication statusPublished - 2012

Keywords

  • Journal Article

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