Different clinical aspects of debrancher deficiency myopathy
- Stefan Kiechla,
- Ursula Kohlendorferb,
- Claudia Thalera,
- Daniela Skladalb,
- Michaela Jakschc,
- Bert Obermaier-Kusserc,
- Johann Willeita
- aDepartment of Neurology, Innsbruck University Clinic, Innsbruck, Austria, bDepartment of Pediatrics, Innsbruck University Clinic, Innsbruck, Austria, cDepartment of Clinical Chemistry, Academic Hospital Schwabing, Munich, Germany
- Dr Stefan Kiechl, Department of Neurology, Innsbruck University Clinic, Anichstrasse 35, A-6020 Innsbruck, Austria. Telephone 00512 504 3886; fax 00512 504 4260; email Stefan.Kiechl{at}uibk.ac.at
- Received 17 November 1998
- Revised 24 February 1999
- Accepted 7 April 1999
Abstract
OBJECTIVE To characterise the main clinical phenotypes of debrancher deficiency myopathy and to increase awareness for this probably underdiagnosed disorder.
METHODS The diagnosis of debrancher deficiency was established by laboratory tests, EMG, and muscle and liver biopsy.
RESULTS Four patients with debrancher deficiency myopathy were identified in the Tyrol, a federal state of Austria with half a million inhabitants. Clinical appearance was highly variable. The following phenotypes were differentiated: (1) adult onset distal myopathy; (2) subacute myopathy of the respiratory muscles; (3) severe generalised myopathy; and (4) minimal variant myopathy. Exercise intolerance was uncommon. The clinical course was complicated by advanced liver dysfunction in two patients and by severe cardiomyopathy in one. All had raised creatine kinase concentrations (263 to 810 U/l), myogenic and neurogenic features on EMG, and markedly decreased debrancher enzyme activities in muscle or liver biopsy specimens. The findings were substantiated by a review of 79 previously published cases with neuromuscular debrancher deficiency.
CONCLUSIONS This study illustrates the heterogeneity of neuromuscular manifestations in debrancher deficiency. Based on the clinical appearance, age at onset, and course of disease four phenotypes may be defined which differ in prognosis, frequency of complications, and response to therapy.
