Redefining the Pediatric Phenotype of X-Linked Monocarboxylate Transporter 8 (MCT8) Deficiency: Implications for Diagnosis and Therapies

X-linked monocarboxylate transporter 8 (MCT8) deficiency results from a loss-of-function mutation in the monocarboxylate transporter 8 gene, located on chromosome Xq13.2 (Allan-Herndon-Dudley syndrome). Affected boys present early in life with neurodevelopment delays but have pleasant dispositions a...

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Bibliographic Details
Published in:Journal of child neurology 2015-10, Vol.30 (12), p.1664-1668
Main Authors: Matheus, Maria Gisele, Lehman, Rebecca K., Bonilha, Leonardo, Holden, Kenton R.
Format: Article
Language:English
Subjects:
Brain - pathology
Child
Child, Preschool
Cohort Studies
Diffusion Tensor Imaging
Dystonia - pathology
Dystonia - physiopathology
Humans
Infant
Magnetic Resonance Imaging
Mental Retardation, X-Linked - diagnosis
Mental Retardation, X-Linked - pathology
Mental Retardation, X-Linked - physiopathology
Mental Retardation, X-Linked - therapy
Muscle Hypotonia - diagnosis
Muscle Hypotonia - pathology
Muscle Hypotonia - physiopathology
Muscle Hypotonia - therapy
Muscular Atrophy - diagnosis
Muscular Atrophy - pathology
Muscular Atrophy - physiopathology
Muscular Atrophy - therapy
Phenotype
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Summary:X-linked monocarboxylate transporter 8 (MCT8) deficiency results from a loss-of-function mutation in the monocarboxylate transporter 8 gene, located on chromosome Xq13.2 (Allan-Herndon-Dudley syndrome). Affected boys present early in life with neurodevelopment delays but have pleasant dispositions and commonly have elevated serum triiodothyronine. They also have marked axial hypotonia and quadriparesis but surprisingly little spasticity early in their disease course. They do, however, have subtle involuntary movements, most often dystonia. The combination of hypotonia and dystonia presents a neurorehabilitation challenge and explains why spasticity-directed therapies have commonly produced suboptimal responses. Our aim was to better define the spectrum of motor disability and to elucidate the neuroanatomic basis of the motor impairments seen in MCT8 deficiency using clinical observation and brain magnetic resonance imaging (MRI) in a cohort of 6 affected pediatric patients. Our findings identified potential imaging biomarkers and suggest that rehabilitation efforts targeting dystonia may be more beneficial than those targeting spasticity in the prepubertal pediatric MCT8 deficiency population.
ISSN:0883-0738
1708-8283
DOI:10.1177/0883073815578524