Table S1. Demographic characteristics of cohort comparing number of affected family members in familial cases.

Familial Familial Variables ≥2 affected 1 affected p-value (n=108) (n=157) Male 31% 34% Gender 0.72 Female 69% 66% Age Years (mean ± SD) 53 ± 13.2 51 ± 13.6 0.25 White/White British 83% 87% Asian/Asian British 9% 7% Ethnicity Black/Black British 1% 3% 0.56 Other 3% 1% No entry 4% 2% ≤10 years 5% 3% 11-20 years 14% 15% 21-30 years 36% 32% Age of onset 0.80 31-40 years 26% 31% 41-50 years 13% 15% ≥51 years 6% 4% Bilateral 69% 69% loss 0.99 Unilateral 31% 31% Yes 74% 68% 0.38 No 26% 32% Yes 42% 31% 0.09 No 58% 69%

SD, standard deviation. Table S2. Demographic characteristics of otosclerosis cohort comparing recruitment pipelines.

Surgical Retrospective Variables p-value (n=436) (n=221) Male 37% 32% Gender 0.24 Female 63% 68% Age at consent Years (mean ± SD) 48 ± 12.6 55 ± 13.5 1x10-9 White/White British 84% 88% Asian/Asian British 9% 4% Ethnicity Black/Black British 2% 3% 0.27 Other 2% 2% No entry 3% 3% ≤10 years 7% 6% 11-20 years 9% 13% 21-30 years 29% 32% Age of onset 0.13 31-40 years 31% 33% 41-50 years 20% 12% ≥51 years 4% 4% Familial 35% 51% Family history 2x10-4 Non-familial 65% 49% Bilateral 60% 67% 0.14 Unilateral 40% 33% Yes 70% 65% Tinnitus 0.21 No 30% 35% Yes 29% 36% Vertigo 0.09 No 71% 64%

SD, standard deviation. Significant differences in bold. Table S3. Demographic characteristics of otosclerosis cohort comparing measles infection.

Measles No Measles Variables p-value (n=299) (n=214) Male 34% 36% Gender 0.65 Female 66% 64% Age at consent Years (mean ± SD) 56 ± 12.6 43 ± 11.6 2x10-29 ≤10 years 7% 7% 11-20 years 11% 15% 21-30 years 24% 33% Age of onset 2x10-3 31-40 years 31% 31% 41-50 years 21% 13% ≥51 years 6% 1%

SD, standard deviation. Significant differences in bold.

50%

40% ** 30%

20%

10% Numberofpatients (%)

0% <10 11-20 21-30 31-40 41-50 51+ Age of onset (yrs)

Measles No Measles

Figure S1. Age of onset in otosclerosis cases comparing measles infection. Measles, n=299; No measles; n=214. **, p < 0.01.

Table S4. Demographic characteristics of cohort.

Variables n=154 Male 35% Gender Female 65% Age at surgery Years (mean ± SD) 46 ± 12.8 White/White British 84% Asian/Asian British 10% Ethnicity Black/Black British 3% Other 1% No entry 3%

SD, standard deviation.

Table S5. Pure-tone audiometry of otosclerosis cohort.

Frequency AC BC ABG (kHz) Pre-op Post-op Pre-op Post-op Pre-op Post-op 0.5 61.0 28.4 21.9 20.0 39.0 8.5 1 59.1 29.3 25.5 22.2 33.6 7.1 2 54.6 32.0 35.7 31.2 18.9 0.7 3 54.4 32.6 30.1 27.9 24.3 4.7 4 57.1 37.1 24.8 25.3 32.3 11.9 PTA 57.3 30.6 28.3 25.3 29.0 5.2

Mean air-conduction (AC) and bone-conduction (BC) thresholds and air-bone gap (ABG) for individual and pure-tone average (PTA) values (n=154).

Table S6. Surgical outcomes.

Post-op ABG AC improvement BC worsened by ≤10 dB 88% <20 dB 25% <5 dB 86% 11-20 dB 10% ≥20 dB 75% ≥5 dB 14% >20 dB 2%

Successful surgery measured as: air-bone gap (ABG) closure ≤10 dB, improvement in air- conduction (AC) thresholds ≥ 20 dB or bone-conduction (BC) not worsened by ≥ 5 dB.

Figure S2. Pre- and post-operative differences in pure-tone audiometry comparing gender and comparing family history. (A) Air- conduction (AC) and (B) bone-conduction (BC) thresholds and (C) air-bone gap (ABG) in male and female cases (Male, n=54; Female; n=100). (D) AC and (E) BC thresholds and (F) ABG in familial and non-familial cases (Familial, n=57; Non-familial; n=97). Familial cases were defined as having 1 or more affected family member. Error bars indicate standard error of mean. *, p < 0.05.

Figure S3. Pre- and post-operative differences in pure-tone audiometry comparing pregnancy characteristics. (A) Air-conduction (AC) and (B) bone-conduction (BC) thresholds and (C) air-bone gap (ABG) in pregnant (Preg_Y, n=77) and not pregnant cases (Preg_N; n=22). (D) AC and (E) BC thresholds and (F) ABG in pregnant cases with hearing changes (Preg_HC, n=23) and without hearing changes during pregnancy (Preg_NC; n=52). Error bars indicate standard error of mean.