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Open Access Highly Accessed Research

The neurology of rhizomelic chondrodysplasia punctata

Annemieke M Bams-Mengerink1, Johannes HTM Koelman2, Hans Waterham3, Peter G Barth1 and Bwee Tien Poll-The14*

Author Affiliations

1 Department of Pediatric Neurology/Emma Children’s Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands

2 Department of Neurology, Academic Medical Center of Amsterdam, Amsterdam, The Netherlands

3 Laboratory of Genetic Metabolic Diseases, Academic Medical Center of Amsterdam, Amsterdam, The Netherlands

4 Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands

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Orphanet Journal of Rare Diseases 2013, 8:174  doi:10.1186/1750-1172-8-174

Published: 30 October 2013

Abstract

Background

To describe the neurologic profiles of Rhizomelic chondrodysplasia punctata (RCDP); a peroxisomal disorder clinically characterized by skeletal abnormalities, congenital cataracts, severe growth and developmental impairments and immobility of joints. Defective plasmalogen biosynthesis is the main biochemical feature.

Methods

Observational study including review of clinical and biochemical abnormalities, genotype, presence of seizures and neurophysiological studies of a cohort of 16 patients with RCDP.

Results

Patients with the severe phenotype nearly failed to achieve any motor or cognitive skills, whereas patients with the milder phenotype had profound intellectual disability but were able to walk and had verbal communication skills. Eighty-eight percent of patients developed epileptic seizures. The age of onset paralleled the severity of the clinical and biochemical phenotype. Myoclonic jerks, followed by atypical absences were most frequently observed. All patients with clinical seizures had interictal encephalographic evidence of epilepsy. Visual evoked (VEP) and brain auditory potential (BAEP) studies showed initial normal latency times in 93% of patients. Deterioration of VEP occurred in a minority in both the severe and the milder phenotype. BAEP and somatosensory evoked potentials (SSEP) were more likely to become abnormal in the severe phenotype. Plasmalogens were deficient in all patients. In the milder phenotype levels of plasmalogens were significantly higher in erythrocytes than in the severe phenotype. Phytanic acid levels ranged from normal to severely increased, but had no relation with the neurological phenotype.

Conclusion

Neurodevelopmental deficits and age-related occurrence of seizures are characteristic of RCDP and are related to the rest-activity in plasmalogen biosynthesis. Evoked potential studies are more likely to become abnormal in the severe phenotype, but are of no predictive value in single cases of RCDP.

Keywords:
Rhizomelic chondrodysplasia punctata; Skeletal dysplasia; Peroxisome; Plasmalogen; Intellectual disability; Epilepsy; Evoked potentials