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Fundamento y objetivo Caracterizar los defectos moleculares y estudiar su distribucion en los portadores de betatalasemia de Lanzarote. Pacientes y metodo El estudio molecular del gen beta de la globina se llevo a cabo con la tecnica de reaccion en cadena de la polimerasa (PCR) en tiempo real (RT-PCR LyghtCycler, Roche), PCR con amplificacion de alelos especificos (PCR-ARMS) y secuenciacion automatica del ADN del gen beta de la globina. Resultados Se incluyo en el estudio a 243 portadores diagnosticados de betatalasemia heterocigota entre julio de 1991 y febrero de 2007. La RT-PCR identifico la lesion molecular en el 81% de los cromosomas [113 codon CD 39 (C → T); 41 IVS-1-nt-110 (G → A), 25 IVS 1-nt-1 (G → A) y 19 IVS 1-nt-6 (T → C)]. Las 12 alteraciones moleculares restantes incluyeron la delecion 619 bp (7,8%) y las mutaciones -28 (A → G), IVS1-nt-2 (T → G), CD 41/42 (-TTCT), CD 8/9 (+G), CD 51 (-C), CD 22 (G → T), CD 24 (T → A), CD 67 (-TG), ademas de una nueva mutacion CD20/21-TGGA. Conclusiones La distribucion de las mutaciones de la betatalasemia heterocigota en Lanzarote es similar a la descrita en la zona mediterranea. El aumento de los flujos migratorios a la comunidad canaria puede explicar la presencia de mutaciones no descritas antes en nuestra comunidad.

This study aimed at assessing the relationship between thrombosis, hyperhomocysteinemia and vitamin B12 deficiency using a case–control study carried out in 326 patients with thrombosis (case group) and 351 patients from the same hospital (control group). Apart from the classic risk factors, a number of hematological variables were evaluated, including serum vitamin B12 (B12), red cell folate (RCF), and serum homocysteine (Hcy). An evaluation of serum methylmalonic acid (MMA) and a clinical study were carried out to investigate B12 pathology. Results of univariate analysis demonstrated decreased B12 levels in thrombosis (Student’s t test, p < 0.0001). Vitamin B12 below 200 pmol/l (LB200) or below 150 pmol/l (LB150), and red cell folate below 600 nmol/l were found in 17.2, 8.6, and 2.2% of cases with thromboembolism, respectively. An increase in Hcy was detected in 86 cases with thrombosis (26.3%). An abnormality in vitamin B12 and/or renal function was found in 80% of cases with hyperHcy and thrombosis. The MMA increase demonstrated that vitamin B12 deficiency was present in these patients with low levels of vitamin B12 in serum, and the MMA levels were in concordance with Hcy levels. The clinical study revealed B12 malabsorption in most cases with LB200. Multivariate analysis showed that serum vitamin B12 (RR 0.998, CI 0.997–0.999) was moderately related to thromboembolism. The results indicated that vitamin B12 deficiency was common among patients with hyperhomocysteinemia and thrombosis. Moreover, HyperHcy was caused by vitamin B12 deficiency and/or chronic renal failure in most patients with thrombosis. As the main cause of vitamin B12 deficiency was vitamin malabsorption, parenteral vitamin B12 with or without folic acid should be administered for the treatment of this condition. However, it remains to be demonstrated whether this treatment approach prevents recurrent thromboses in patients with vitamin B12 deficiency and thrombosis, as suggested by some case reports.