A study of serum immunoglobulin G, A, M and E levels in 107 pairs of Iraqi twins was carried out. The results suggest strong evidence for genetic as well as environmental factors in all four immunoglobulin levels.
Al-Agidi, Saad K.
"Serum Immunoglobulin Levels in Iraqi Twins,"
3, Article 4.
Available at: https://digitalcommons.wayne.edu/humbiol/vol52/iss3/4