Asian immigration and public health in California: thalassemia in newborns in California.

Objective: This study reviews Asian immigration in California and the effect it has had on public health in the state in terms of genetic disease detection. This is documented in terms of the numbers of cases of thalassemia detected, including Hemoglobin (Hb) E/beta-thalassemia, beta-thalassemia major, and Hb H disease.

Methods: California has been screening all newborns for hemoglobinopathies since 1990 and tests approximately 530,000 newborns per year. Samples are collected on filter paper during the first I to 2 days of life and sent to one of eight contract laboratories. The screening methodology is cation exchange high-performance liquid chromatography. Confirmatory testing is performed at Children's Hospital Oakland hemoglobin laboratory using a variety of methods.

Results: Approximately five to seven cases each of Hb E/beta-thalassemia and beta-thalassemia major are detected annually. Most cases are of Southeast Asian origin. Prevalence rate of Hb E/beta-thalassemia among Southeast Asians is approximately 1 in 2,200 births. A pilot program for Hb H disease screening was successful and this disorder has now been incorporated in newborn screening, detecting approximately 40 cases per year.

Conclusions: Increases in Asian immigration and births in the U.S., particularly California, have been dramatic during the past 10 years and have led to detection of previously rare diseases like Hb E/beta-thalassemia. It has also changed the way other thalassemic disorders are viewed, such as Cooley anemia, which previously affected mainly individuals of Mediterranean origin. Now, most affected patients are of Asian origin.