Measurement of the apparent diffusion coefficient in paediatric mitochondrial encephalopathy cases and a comparison of parenchymal changes associated with the disease using follow-up diffusion coefficient measurements

OBJECTIVES

To reveal the contribution of MRI and diffusion-weighted imaging (DWI) to the diagnosis of mitochondrial encephalopathy (ME) and to evaluate the parenchymal changes associated with this disease in the involved parenchymal areas using the apparent diffusion coefficient (ADC) parameter.

METHODS

Ten patients who had undergone MRI and DWI analysis with a pre-diagnosis of neurometabolic disease, and who were subsequently diagnosed with ME in laboratory and/or genetic studies, were included in our study. ADC values were compared with a control group composed of 20 patients of similar age with normal brains. Evaluations involved measurements made in 20 different areas determined on the ADC map. The dominance or contribution of ADC coefficient measurements to the conventional sequences was compared with the controls.

RESULTS

In the first examination, an increase in both diffusion and ADC values was detected in six cases and diffusion restriction and a decrease in ADC values in three patients. While an increase in both diffusion and ADC values was demonstrated in four cases, there was diffusion restriction and a decrease in ADC values in three cases in the control examinations.

CONCLUSIONS

DWI provides information that complements conventional MRI sequences in the diagnosis of ME.

Heterogeneity of Marinesco-Sjögren syndrome: report of two cases

Marinesco-Sjögren syndrome is an autosomal recessive, multiorgan disorder with cardinal features of cerebellar ataxia, congenital or early childhood cataracts, psychomotor retardation, myopathy, and short stature. Mutations in the SIL1 gene on chromosome 5q31 were demonstrated to cause Marinesco-Sjögren syndrome. We describe two Turkish patients with clinical characteristics of Marinesco-Sjögren syndrome, but without mutations in SIL1. These two patients also manifested cerebral white matter involvement in cranial imaging, which was previously described in Marinesco-Sjögren syndrome. Marinesco-Sjögren syndrome is genetically heterogeneous, and mutations of SIL1 are often not evident. Consequently, we presume that new genes for Marinesco-Sjögren syndrome await discovery. New genes hold the promise of furthering the mechanistic understanding of the condition, enabling clinically meaningful genetic classification schemes to be designed.

Case report of intrafamilial variability in autosomal recessive centronuclear myopathy associated to a novel BIN1 stop mutation

Centronuclear myopathies (CNM) describe a group of rare muscle diseases typically presenting an abnormal positioning of nuclei in muscle fibers. To date, three genes are known to be associated to a classical CNM phenotype. The X-linked neonatal form (XLCNM) is due to mutations in MTM1 and involves a severe and generalized muscle weakness at birth. The autosomal dominant form results from DNM2 mutations and has been described with early childhood and adult onset (ADCNM). Autosomal recessive centronuclear myopathy (ARCNM) is less characterized and has recently been associated to mutations in BIN1, encoding amphiphysin 2. Here we present the first clinical description of intrafamilal variability in two first-degree cousins with a novel BIN1 stop mutation. In addition to skeletal muscle defects, both patients have mild mental retardation and the more severely affected male also displays abnormal ventilation and cardiac arrhythmia, thus expanding the phenotypic spectrum of BIN1-related CNM to non skeletal muscle defects. We provide an up-to-date review of all previous cases with ARCNM and BIN1 mutations.