RESUMO
OBJECTIVE: Wolfram syndrome (WS) is a severe autosomal recessive pleiotropic disease primarily characterized by the association of juvenile-onset diabetes mellitus and optic atrophy. Earlier reports have shown that a proportion of WS cases may remain unrecognized due to misdiagnosis as type 1 diabetes mellitus (T1DM). The objectives of this work were to estimate the prevalence of patients fulfilling clinical criteria for WS in a cohort of subjects diagnosed as T1DM and to identify causal WFS1 gene mutations in those individuals meeting clinical criteria for the disease. METHODS: A cohort of 131 unrelated Mexican T1DM patients was collected, including 77 females and 54 males. Additional clinical anomalies suggesting WS were identified through review of medical files, detailed physical examination and/or specialized tests. WFS1 gene analysis was performed using exon-by-exon PCR amplification and direct Sanger sequencing on genomic DNA from patients reaching WS clinical criteria. RESULTS: Clinical criteria for a WS diagnosis were reached in 6 probands, corresponding to a 4.58% frequency of the disease. WFS1 mutations were identified in 4 out of 5 (80%) individuals fulfilling WS clinical criteria, including two homozygous, one compound heterozygous, and one patient with a single allele mutation. No WFS1 mutations were identified in the remaining subject. CONCLUSIONS: In our cohort, approximately 6% of cases diagnosed as T1DM were in fact patients with Wolfram syndrome. WFS1 mutations were identified in 4 out of 5 individuals (80%) fulfilling clinical criteria for WS. Clinical and genetic analyses of large cohorts of T1DM patients from different ethnic origins would help to better estimate the occurrence of WS and will lead to a better management of such patients.