Non-radioactive Southern hybridization for early diagnosis of alpha-thalassemia with Southeast Asian-type deletion in Taiwan

alpha -Thalassemia has been estimated to account for over 60% of hydrops fe talis cases in Taiwan, The most common genotypic lesion found in ol-thalass emia-l cases in Taiwan is deletion of a large segment of the ac-globin gene cluster, termed the Southeast Asian-type deletion (-(SEA)/; further referr ed to as SEA-type deletion), Seven chorionic villus samples (CVS) from preg nancies of couples both heterozygous for SEA-type deletion were studied. No n-radioactive Southern-blot hybridization using the digalkaline phosphatase detection system was developed to fulfill this purpose. The results were c ompared with corresponding polymerase chain reaction (PCR) data to elucidat e the effectiveness of these two protocols in the diagnosis of the SEA-type deletion. The data showed that of the seven CVS, three demonstrated a dist inctive band pattern, indicating their homozygous status of SEA-type deleti on, whereas two showed heterozygous patterns, and the other two were free o f the deletion, Homozygosity of the deletion was confirmed by Southern-blot hybridization performed on DNA samples extracted from the abortus tissue. However, two of the three cases with SEA-type deletion showed heterozygous PCR results. Maternal cell contamination could be responsible for the artif acts in the PCR results, but the influence due to the contamination is mini mal in non-radioactive Southern-blot hybridization, We concluded that PCR i s suitable for screening of carrier adults with SEA-type deletion, and non- radioactive Southern hybridization is ideal for early prenatal diagnosis of the SEA-type deletion. (C) 2000 Wiley Liss, Inc.