35 unrelated individuals were studied for characterization as either heterozygous or homozygous for beta-thalassemia. Molecular analysis was done by PCR/RFLP to detect the mutations most commonly associated with beta-thalassemia (β0IVS-I-1, β+IVS-I-6, and β039). In the patients who showed none of these mutations, the beta-globin genes were sequenced. Of the 31 heterozygous patients, 13 (41.9%) had the β+IVS-I-6 mutation, 15 (48.4%) the β0IVS-I-1 mutation, 2 (6.5%) the β+IVS-I-110 mutation and 1 (3.2%) the β+IVS-I-5 mutation. IVS-I-6 was detected in the four homozygotes. The mutation in codon 39, often found in previous studies in Brazil, was not detected in the present case. This is the first study aiming at identifying mutations that determine beta-thalassemia in the state of Rio Grande do Norte.

βS haplotypes were studied in 47 non-related patients with sickle-cell anemia from the state of Rio Grande do Norte, Brazil. Molecular analysis was conducted by PCR/RFLP using restriction endonucleases XmnI, HindIII, HincII and HinfI to analyze six polymorphic sites from the beta cluster. Twenty-seven patients (57.5%) were identified with genotype CAR/CAR, 9 (19.1%) CAR/BEN, 6 (12.8%) CAR/CAM, 1 (2.1%) BEN/BEN, 2 (4.3%) CAR/Atp, 1 (2.1%) BEN/Atp and 1 (2.1%) with genotype Atp/Atp. The greater frequency of Cameroon haplotypes compared to other Brazilian states suggests the existence of a peculiarity of African origin in the state of Rio Grande do Norte.

Acute intermittent porphyria (AIP, OMIM 176000) is an autosomal dominant metabolic disease caused by mutations in the gene encoding hydroxymethylbilane synthase (HMBS; EC 4.3.1.8; formely named porphobilinogen deaminase, PBGD), mapped to chromosome 11q23.3. We describe a novel mutation of the HMBS gene, a de novo 3-base deletion in the splicing donor site of intron 3 (IVS3+2_4delTGG) in a woman affected by AIP. RT-PCR analysis revealed an abnormal HMBS mRNA, compatible with exon 3 skipping.