New Clinical Implications of Molecular Genetics

The article by Dozy et al (p 1610) reflects the advent of a new era in medicine and medical genetics—the application of techniques from molecular biology to the solution of clinical problems. This important development has resulted from recent major advances in isolating and deciphering specific human gene sequences. Dozy et al as well as Orkin and colleagues¹ were able to diagnose certain hemoglobinopathies antenatally by the detection of an abnormal pattern of DNA fragments in fetal cells. Antenatal detection of hemoglobinopathies from globin gene deletion is now made possible by analysis of cells recovered by the relatively simple and safe method of early second trimester amniocentesis. Clinically important deletion syndromes include α-thalassemia and δ-β-thalassemia.² A more difficult and less reliable method for detection of hemoglobin abnormalities, which requires fetal blood sampling by placental puncture or under direct vision, carries a substantial risk (up to 10%) of fetal