Table 2.

Secular Trend in the Frequency of Pathologic GJB2 and GJB6 Mutations among the Deaf: 1920–1980

	Birth Cohorts
Statistic	1920–1940	1941–1960	1961–1980	Total
Number of Subjects	87	170	184	441
Number of Genes	174	340	368	882
Number of Mutations	49	122	143	314
Frequency of Mutations (%)	28	36	39	36

Linear-trend analysis: Z score 2.33, p < 0.01 (one-sided).