British zyxwvutsrqponml Journal zyxwvutsrqponm ofHaematology, 1995. zyxwvut 90, 483-485 SHORT REPORT A promoter mutation, C zyxw -+ T at position - 92, leading to silent P-thalassaemia MARIA CRISTINA ROSATELLI, VALERIA FAA, ALESSANDRA MELONI, FLAVIA FIORENZA,* RBNZO GALANELLO; DANIELA GASPERINI,~ GIOVANNI AMENDOLA$ AND ANTONIO CAO Istituto di Clinica e Biologia dell’Eth Evolutiva, Universith degli Studi di Cagliari, *Ospedale S. Elia Caltanissetta, tospedale Regionale per Le Microcitemie, USL 21, Cagliari, SDivisione Pediatria, Ospedale Castellammare di Stabia Received 15 November 1994; accepted for publication zyxwvuts 22 March 2995 zyxw Summary. This study describes the clinical phenotype of the mutation ($39) (two cases) or severe @-thalassaemia zy (p’ C .--) T mutation at position - 92 of the Pglobin gene. IVSII nt zyxwv 745) (two cases) developed thalassaemia inter- Excluding two cases with HbA2 levels within the range of media. According to these characteristics,the -92 promoter the b-thalassaemia carrier state, heterozygotes for this mutation should be added to the list of silent Pthalassaemias. mutation showed normal or borderline red blood cells count, Hb levels, MCV, MCH and HbA2 values, and Keywords: silent Pthalassaemia, promoter mutation, unbalanced globin chain synthesis. Compound hetero- thalassaemia intermedia. zygotes for the - 92 C -+ T mutation and a p” thalassaemia Silent P-thalassaemiasare thalassaemicdisorders character- ized by normal red cell indices, normal HbA2 and F levels and are defined only by unbalanced globin chain synthesis (for review see Cao & Rosatelli, 1993). Because of these characteristics, these determinants may be missed by the procedures commonly in use for carrier identification. The compound heterozygous states for typical and silent p- thalassaemias most commonly result in the clinical phenotype of thalassaemia intermedia. The most common silent P-thalassaemia is the C -+ T substitution at position -101 from the CAP site within the distal CACCC box (Gonzales-Redondo et al, 1989). Less common types of silent P-thalassaemia are the A + C mutation at CAPsite +1 (Wong et al, 1987), the C -+ G mutation at nt 6 3’ zyxwvu to the termination codon (Jankovic et al, 1991), the C -+ G mutation at nt 844 of the IVSII (Murru et al. 1991) and the AATAAA + AATAAG mutation in the polyadenylation signal (Kazazian & Boehm, 1988). A rare p-thalassaemia mutation, C --f T at position -92, has been reported recently in two heterozygoteswho showed nearly normal haematological values, and in a patient with sickle-cell P-thalassaemia with a very mild clinical picture (Divoky et al, 1993). In this paper we report the clinical phenotype of 13 Correspondence: Dr M. Cristina Rosatelli, Istituto di Clinica e Biologia dell’Eta Evolutiva, via Tenner s/n. 09121 Cagliari, Italy. zyxwvut 0 1995 Blackwell Science Ltd heterozygotes for the -92 (C -+ T) mutation and four patients compound heterozygous for the -92 (C+ T) mutation and severe P-thalassaemia. The data indicate that the -92 (C + T) mutation belongs to the category of silent P-thalassaemias. PATIENTS AND METHODS Four families (two from Campania, one from Po Delta region and one from Sicily) were referred to our Centre for molecular characterization of their P-thalassaemia defect. Routine haematological studies were performed by standard methods. Genomic DNA was isolated from peripheral blood leucocytes using standard procedure. Screening for the eight most common P-thalassaemia mutations in the Mediterra- nean area was performed by reverse dot-blot analysis on amplified DNA. In cases in whom no mutation was detected by this approach, we carried out DGGE analysis followed by direct sequencing. Sequencing analysis was performed by using the dideoxy chain termination method of Sanger. RESULTS In the four families investigated, DGGE and sequencing analysis led to the detection of 13 heterozygotes for the C + T mutation at position -92 (Fig 1). All these subjects showed normal or borderline red blood cells count, Hb levels, 483