In order to determine the contribution of a-thalassemia to microcytosis and hypochromia, 339 adult outpatients seen at Unicamp University Hospital (with the exception of the Clinical Hematology outpatient clinics), who showed normal hemoglobin (Hb) levels and reduced mean corpuscular volume and mean corpuscular hemoglobin, were analyzed. Ninety-eight were Blacks (28.9%) and 241 were Caucasians (71.1%). In all cases, Hb A 2 and F levels were either normal or low. The most common deletional and nondeletional forms of a-thalassemia [-a 3.7 , -a 4.2 , --MED , -(a) 20.5 , a HphI a, a NcoI a, aa NcoI and a TSAUDI ] were investigated by PCR and restriction enzyme analyses. A total of 169 individuals (49.9%) presented a-thalassemia: 145 (42.8%) were heterozygous for the -a 3.7 deletion (-a 3.7 /aa) and 18 (5.3%) homozygous (-a 3.7 /-a 3.7 ), 5 (1.5%) were heterozygous for the nondeletional form a HphI a (a HphI a/aa), and 1 (0.3%) was a --MED carrier (--MED /aa). Among the Blacks, 56 (57.1%) showed the -a 3.7 / aa genotype, whereas 12 (12.2%) were -a 3.7 /-a 3.7 and 1 (1.0%) was an a HphI a carrier; among the Caucasians, 89 (36.9%) were -a 3.7 /aa, 6 (2.5%) had the -a 3.7 /-a 3.7 genotype, 4 (1.7%) presented the nondeletional form (a HphI a/aa), and 1 (0.4%) was a --MED carrier. These results demonstrate that a-thalassemia, mainly through the -a 3.7 deletion, is an important cause of microcytosis and hypochromia in individuals without anemia. These data are of clinical relevance since these hematological alterations are often interpreted as indicators of iron deficiency.

To compare the features of sickle-cell anemia in Brazil with those in other locales, we studied the effects of the beta-globin-like gene cluster haplotype and alpha-thalassemia upon the clinical and hematological features in 85 patients. The distribution of haplotypes differed from that in the United States and Jamaica. The Central African Republic (CAR) haplotype predominated; 34% of patients were CAR haplotype homozygotes, 45% CAR/Benin homozygotes, and 11% Benin homozygotes. No Senegal haplotype chromosomes were observed. Alpha-thalassemia was present in 17.5% of patients. HbF levels were higher in Benin homozygotes, compared with the other two groups (P < 0.05). Nearly half the patients with a CAR haplotype had leg ulcers, compared to 12.5% of the Benin homozygote group; stroke did not occur in alpha-thalassemia carriers, but neither result was statistically significant. As in other studies, our results indicate that the CAR haplotype may be associated with more severe disease.

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In this study we have determined the frequency of β^s haplotypes in a Brazilian sickle cell disease population from Sao Paulo, Brazil, by analyzing sequence variations in the immediate 5’ flanking and second intervening sequence (IVSII) regions of the γ globin genes. This association between sequence differences and β^s haplotype backgrounds was determined by screening genomic DNA samples using dot blot analysis of polymerase chain reaction products. We studied 148 β^s chromosomes, and found that haplotype 20 (CAR or Bantu) significantly predominated in this population. This is in agreement with the findings of the historical Portuguese Atlantic slave trade from Africa to South America.