Variable clinical expressivity of STAT3 mutation in hyperimmunoglobulin E syndrome: genetic and clinical studies of six patients

Autosomal dominant Hyper IgE syndrome (AD-HIES) is a rare and complex primary immunodeficiency that affects multiple systems. Mutations in signal transducer and activator of transcription 3 (STAT3) gene cause AD-HIES. These mutations have a dominant-negative effect and the presence of such mutations is associated with a clinical phenotype. We aim to describe genetic and clinical characteristics of patients with AD-HIES in our clinic and to highlight the variability of clinical patterns in the same family. We describe six patients, four individuals of the same family and two unrelated patients. All patients were given a clinical score based on disease phenotype according to the National Institute of Health (NIH) score. Mutation analysis of STAT3 was done by PCR amplification of all coding exons followed by bidirectional sequencing using the BigDye kit v1.1 and an ABI3700 genetic analyzer (Applied Biosystems). All six patients had DNA binding region point mutations: a proband and his three children with p.Phe384Leu mutation, a patient with p.Arg382Trp substitution and a patient with p.Arg382Gln mutation. All of these mutations were previously reported. Patients differed in infectious, immunologic and somatic features. We observed an extreme variability in disease phenotype within the reported family with one genetically affected patient displaying an 'unaffected' phenotype. Although the genetic cause of AD-HIES is known, more studies are required to better understand the possible additional factors that may affect disease expressivity within families and the clinical diversity of the disease