Adult polyglucosan body disease-an atypical compound heterozygous with a novel GBE1 mutation

Introduction: Adult polyglucosan body disease (APBD) is an autosomal recessive leukodystrophy characterized by neurogenic bladder starting after 40 years old, spastic paraparesis and peripheral neuropathy. It is mainly resultant from the GBE1 homozygous p.Tyr329Ser (c.986A>C) mutation, especially in Ashkenazi-Jewish patients, although some cases of compound heterozygous have been reported. A genotype-phenotype correlation is not established, but atypical phenotypes have been described mainly in non-p.Tyr329Ser pathogenic variants.

Case report: We describe an atypical case in a 62-year-old Portuguese woman, presenting the typical clinical triad of APBD plus prominent autonomic dysfunction, suggested by orthostatic hypotension and thermoregulatory dysfunction; she has compound heterozygous GBE1 mutations, namely, p.Asn541Asp (c.1621A>G) and p.Arg515Gly (c.1543C>G), the last one not yet reported in literature and whose pathogenicity was suggested by bioinformatics analysis and confirmed by sural nerve biopsy that showed intra-axonal polyglucosan bodies.

Discussion: Besides the report of a novel GBE1 mutation, this case also expands the phenotypic spectrum of this disorder, reinforcing autonomic dysfunction as a possible and prominent manifestation of APBD, mimicking autosomal dominant leukodystrophy with autonomic disease in some way. Therefore, we questioned a possible relationship between this genotype and the phenotype marked by dysautonomia. Additionally, we review previously reported cases of APBD in non-homozygous p.Tyr329Ser patients with atypical phenotypes.