Frequency of Fabry disease in a juvenile idiopathic arthritis cohort

BACKGROUND: Fabry disease (FD) is a rare, X-linked, multisystemic lysosomal storage disorder (LSD) that results from a deficiency in the hydrolase alpha-galactosidase A (⍺-GalA). During childhood, classic FD symptomatology is rare. The majority of children may show non-specific symptoms, including in the musculoskeletal system. The prevalence of FD among juvenile idiopathic arthritis (JIA) patients is unknown. OBJECTIVE: This study aimed to identify the frequency of FD in a JIA cohort, characterizing early clinical symptoms, enzyme titers, and GLA genotyping. METHODS: Children with JIA followed in a tertiary Children Hospital cohort were selected. Clinical, laboratory and familiar information were recorded. Molecular genetic testing to detect GLA gene mutations was performed in girls and enzymatic analysis in boys. RESULTS: In 89 patients (56.2% female, age at disease onset: 8.93 ± 4.35 years), one male (1.12%) patient presented pathogenic mutation in GLA gene, c.1244 T > C p.L415P, one female patient had a variant of uncertain significance c.38C > T (p.Ala13Val). Three additional (3.4%) patients had the enzymatic activity of alpha-galactosidase slightly decreased. We observed the presence of intronic variants in 44.44% of patients in our cohort: c.1000-22C > T; c.370-81_-77del; c.640-16A > G; c.10C > T; c.548-125C > G and c.-12G > A. These variants and their combination were associated with clinical symptoms in our cohort. CONCLUSIONS: The incidence of FD in our cohort was 1.12%. Intronic variants were associated with symptoms previously described in the literature. Screening for FD in JIA may be a reasonable strategy for those with an atypical pattern of pain.