High variability of clinical symptoms in a Polish family with a novel THAP1 mutation

Abstract

Background. Mutations in the THAP1 gene are associated with a broad spectrum of dystonia including focal and generalized forms. Missense, nonsense and frameshift mutations, including small insertions/deletions within the THAP1 gene, have been reported and majority of them cause autosomal dominant disease with limited penetrance of approximately 60%. Here, we describe a novel THAP1 mutation. Materials and methods. Blood samples were collected from consenting family members for extraction of genomic DNA. As controls, we analyzed 150 individuals without neurological disorders. THAP1 coding sequences were amplified with PCR and sequenced. Results. We describe a Polish family with a novel heterozygous substitution: c.167A>G (p.Glu56Gly) in THAP1 exon 2. This is the largest reported family with the mutation in THAP1 exon 2. The mutation was found in four of five genetically studied family members, including two clinically affected male individuals and two asymptomatic carriers (male and female). Data on one deceased male symptomatic subject were available and two assumed carriers were identified. The substitution was not present in any of the analyzed healthy controls. The high variability of phenotype included age of onset, localization of the initial symptom as well as the rate and degree of generalization. Conclusions. Our findings strongly suggest the role of other genetic factors or environmental triggers in the pathogenesis of dystonia related to mutations in THAP1 gene.

KEYWORDS:

• dystonia DYT6
• THAP1 gene
• novel mutations
• family
• phenotype