Low Prevalence Estimates of Late-Onset Glycogen Storage Disease Type II in French-Speaking Belgium are not Due to Missed Diagnoses

TY - JOUR

T1 - Low Prevalence Estimates of Late-Onset Glycogen Storage Disease Type II in French-Speaking Belgium are not Due to Missed Diagnoses

AU - Remiche, Gauthier

AU - Lukacs, Zoltan

AU - Kasper, David C

AU - Abramowicz, Marc

AU - Pandolfo, Massimo

PY - 2018

Y1 - 2018

N2 - BACKGROUND: Late-onset glycogen storage disease type II is associated with variable muscle phenotypes. Epidemiological data suggest that its prevalence is lower in Belgium than in bordering countries like The Netherlands.OBJECTIVE: We investigated whether such low estimated prevalence is due to missed diagnoses.METHODS: We screened 100 patients with muscle phenotypes of undetermined origin using a dried blood spot test for alpha-acid glucosidase (GAA) activity. Patients with low activity at screening were re-tested by the same method and, if low activity was confirmed, GAA gene analysis was performed.RESULTS: The screening test revealed lower than normal GAA activity in 15 patients, but in only two of them it was low enough to be considered in the disease range. Retesting confirmed lower than normal GAA activity in five patients, but in all of them it was above the disease range. A single patient carried a heterozygous known pathogenic GAA mutation, whose significance in this case remains undetermined.CONCLUSIONS: We conclude that reported low prevalence estimates in Belgium are not likely to be due to an underdiagnosis bias. Lower prevalence compared to neighbouring The Netherlands may be due to different ethnic stratification of our patients. Diagnostic strategies should keep into account the expected prevalence of a disease in specific populations.

AB - BACKGROUND: Late-onset glycogen storage disease type II is associated with variable muscle phenotypes. Epidemiological data suggest that its prevalence is lower in Belgium than in bordering countries like The Netherlands.OBJECTIVE: We investigated whether such low estimated prevalence is due to missed diagnoses.METHODS: We screened 100 patients with muscle phenotypes of undetermined origin using a dried blood spot test for alpha-acid glucosidase (GAA) activity. Patients with low activity at screening were re-tested by the same method and, if low activity was confirmed, GAA gene analysis was performed.RESULTS: The screening test revealed lower than normal GAA activity in 15 patients, but in only two of them it was low enough to be considered in the disease range. Retesting confirmed lower than normal GAA activity in five patients, but in all of them it was above the disease range. A single patient carried a heterozygous known pathogenic GAA mutation, whose significance in this case remains undetermined.CONCLUSIONS: We conclude that reported low prevalence estimates in Belgium are not likely to be due to an underdiagnosis bias. Lower prevalence compared to neighbouring The Netherlands may be due to different ethnic stratification of our patients. Diagnostic strategies should keep into account the expected prevalence of a disease in specific populations.

KW - Adult

KW - Aged

KW - Belgium/epidemiology

KW - Female

KW - Glycogen Storage Disease Type II/diagnosis

KW - Humans

KW - Male

KW - Middle Aged

KW - Prevalence

KW - Young Adult

U2 - 10.3233/JND-180336

DO - 10.3233/JND-180336

M3 - SCORING: Journal article

C2 - 30175981

VL - 5

SP - 471

EP - 480

JO - J NEUROMUSCULAR DIS

JF - J NEUROMUSCULAR DIS

SN - 2214-3599

IS - 4

ER -