Severe cutaneous adverse drug reactions: diagnostic approach and genetic study in a Brazilian case series.

Summary:Background. Severe cutaneous adverse reactions (SCAR) are potentially fatal reactions. Genetic predisposition is involved in their pathogenesis related to drugs and ethnicities, however in a mixed population these relationships are still unknown. The aim of this study was to describe phenotypes, suspect drugs and HLA-alleles related to SCAR, identified by a systematized approach in a Brazilian case series. Methods. Patients who were diagnosed with SCAR between March 2011 and July 2019 at our university hospital were included. European Network for Drug Allergy (ENDA) questionnaire was used to collect clinical and laboratory data and algorithms for assessment of drug causality were applied. Socio-demographic variables included age, gender and skin color/ethnicity. Drug patch tests (DPT) and HLA-A, -B, -DRB1 typing were carried out. Results. A total of 74 patients were included: 36 (48.64%) with SJS/TEN, 32 (43.24%) DRESS/DIHS, 3 (4.05%) AGEP, 2 (2.70%) overlap(DRESS/SJS and DRESS/AGEP) and 1 (1.35%) GBFDE. The median age was31.5 years (IQR = 14-52.25), most were female (n = 44/59.46%) and brown (n = 38/51.35%). Anticonvulsants (n = 32/43.24%) were the largest group involved and antibiotics (n = 26/35.13%) were the second most common. Two patients with DRESS died during the acute phase. Positive DPT were shown only in anticonvulsant associated DRESS. HLA related to abacavir, allopurinol and carbamazepine were identified. Conclusions. A systematized approach allowed the phenotypic characterization of SCAR. The HLA-A*31:01, B*57:01 and B*58:01 alleles were identified, reinforcing the causality in SCAR by CBZ, ABC and ALLO in the Brazilian population.