Question

in our hospital there are some cases (around 60)who are clinically detected as Alfa thalasemia but not confirmed.in my study i try to confirm their condition (via genetic studies)and detect their serum parameters that can be changed with the alfa thalasemia.please help me to find the statistically best minimum number of cases whom should be involved in the study.though i tried early also,i coudn't post the question.are u taking money?