[1] Vaasa Cent Hosp, Dept Otorhinolaryngol Head & Neck Surg, Vaasa 65100, Finland
[2] Helsinki Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Helsinki, Finland
[3] Univ Turku, Cent Hosp, Dept Audiol, FIN-20520 Turku, Finland
[4] Univ Vaasa, Dept Math & Stat, Vaasa, Finland
[5] Univ Helsinki, Inst Dent, Helsinki, Finland
[6] Univ Helsinki Hosp, Dept Clin Genet, Helsinki, Finland
[7] Turku Univ, Cent Hosp, Dept Otorhinolaryngol Head & Neck Surg, Turku, Finland
[8] Univ Helsinki, Inst Dent, Inst Biotechnol, Helsinki, Finland