Genetic susceptibility to bilateral tinnitus in a Swedish twin cohort.
Genetic contributions to tinnitus have been difficult to determine due to the heterogeneity of the condition and its broad etiology. Here, we evaluated the genetic and nongenetic influences on self-reported tinnitus from the Swedish Twin Registry (STR).



Cross-sectional data from the STR was obtained. Casewise concordance rates (the risk of one twin being affected given that his/her twin partner has tinnitus) were compared for monozygotic (MZ) and dizygotic (DZ) twin pairs (N = 10,464 concordant and discordant twin pairs) and heritability coefficients (the proportion of the total variance attributable to genetic factors) were calculated using biometrical model fitting procedures.



Stratification of tinnitus cases into subtypes according to laterality (unilateral versus bilateral) revealed that heritability of bilateral tinnitus was 0.56; however, it was 0.27 for unilateral tinnitus. Heritability was greater in men (0.68) than in women (0.41). However, when female pairs younger than 40 years of age were selected, heritability of 0.62 was achieved with negligible effects of shared environment.



Unlike unilateral tinnitus, bilateral tinnitus is influenced by genetic factors and might constitute a genetic subtype. Overall, our study provides the initial evidence for a tinnitus phenotype with a genetic influence.Genet Med advance online publication 23 March 2017.
Department of Psychosomatic Medicine, Center for Internal Medicine and Dermatology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Iris Lianne
IL
Maas
Tinnitus Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Petra
P
Brüggemann
Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO - Center for Genomics and Oncological Research-Pfizer, University of Granada, Junta de Andalucía, PTS, Granada, Spain.
Teresa
T
Requena
Department of Mathematics, University of Bergen, Bergen, Norway.
Jan
J
Bulla
Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Niklas K
0000-0002-6427-1198
NK
Edvall
Department of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, Odense, Denmark.
Jacob V B
0000-0001-9630-9149
JVB
Hjelmborg
Department of ORL, Head and Neck Surgery, Research Laboratory, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Agnieszka J
0000-0002-9292-6606
AJ
Szczepek
Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Barbara
B
Canlon
Tinnitus Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Birgit
B
Mazurek
Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO - Center for Genomics and Oncological Research-Pfizer, University of Granada, Junta de Andalucía, PTS, Granada, Spain.|Department of Otolaryngology, Complejo Hospitalario Universidad de Granada (CHUGRA), ibs.granada, Granada, Spain.
Jose A
JA
Lopez-Escamez
Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Christopher R
0000-0001-7267-5136
CR
Cederroth
D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D040582:Inheritance Patterns; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries; D012306:Risk; D013548:Sweden / Q000453:epidemiology; D014012:Tinnitus / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult