Different clinical aspects of debrancher deficiency myopathy

Objective-To characterise the main clinical phenotypes of debrancher defici ency myopathy and to increase awareness for this probably underdiagnosed di sorder. Methods-The diagnosis of debrancher deficiency was established by laborator y tests, EMG, and muscle and liver biopsy. Results-Four patients with debrancher deficiency myopathy were identified i n the Tyrol, a federal state of Austria with half a million inhabitants. Cl inical appearance was highly variable. The following phenotypes were differ entiated: (1) adult onset distal myopathy; (2) subacute myopathy of the res piratory muscles; (3) severe generalised myopathy; and (4) minimal variant myopathy. Exercise intolerance was uncommon. The clinical course was compli cated by advanced liver dysfunction in two patients and by severe cardiomyo pathy in one. All had raised creatine kinase concentrations (263 to 810 U/l ), myogenic and neurogenic features on EMG, and markedly decreased debranch er enzyme activities in muscle or liver biopsy specimens. The findings were substantiated by a review of 79 previously published cases with neuromuscu lar debrancher deficiency. Conclusions-This study illustrates the heterogeneity of neuromuscular manif estations in debrancher deficiency. Based on the clinical appearance, age a t onset, and course of disease four phenotypes may be defined which differ in prognosis, frequency of complications, and response to therapy.