Molecular characterization of beta-thalassemia mutations in Guadeloupe.
In order to perform genetic counselling and prenatal diagnosis of Hb-S-beta-thalassemia disease and beta-thalassemia, we have delineated the spectrum of beta-thalassemia alleles in the Guadeloupean population. A sample of 63 unrelated families was analyzed including 70 beta-thalassemia carriers, 52 Hb-S-beta-thalassemia, and 8 patients with different beta-thalassemic hemoglobinopathies. Among the eleven mutations identified, four of them [-29 (A --> G), IVS-I-5 (G --> A), IVS-II-1 (G --> A), and IVS-I-5 (G --> C)] account for 77.6% of the beta-thalassemia chromosomes present in the studied families. The seven other variants, CD 24 (T --> A), IVS-I-2 (T --> C), Poly A (T --> C), -88 (C --> T), IVS- 11-849 (A --> G), Hb E, and Hb Lepore are less frequent. As a result, Hb S-beta+-thalassemia type 1 (low Hb A values: 5-15%) together with Hb S-beta(omicron)-thalassemia phenotypes are as frequent as Hb S-beta+-thalassemia type 2 (high Hb A values: 20-30%) in the Guadeloupean population. Patients with Hb S-beta+-thalassemia type 2 have milder hematological manifestations of the disease compared to patients with Hb S-beta(omicron)-thalassemia and Hb S-beta+-thalassemia type 1. This first report on the type and nature of beta-thalassemia mutations in Guadeloupe shows that prenatal diagnosis of Hb S-beta-thalassemia and beta-thalassemia should be feasible by direct detection of point mutation in most cases.
Romana
M
M
Unité de Recherche sur la Drépanocytose, INSERM U 359, Pointe-à-Pitre, Guadeloupe.
Keclard
L
L
Guillemin
G
G
Lavocat
E
E
Saint-Martin
C
C
Berchel
C
C
Mérault
G
G
D000354:Africa, Western / Q000208:ethnology; D000483:Alleles; D000755:Anemia, Sickle Cell / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics; D005787:Gene Frequency; D005817:Genetic Counseling; D005914:Globins / Q000235:genetics*; D019430:Guadeloupe / Q000453:epidemiology; D006451:Hemoglobin, Sickle / Q000235:genetics; D006801:Humans; D007194:India / Q000208:ethnology; D019083:Mediterranean Region / Q000208:ethnology; D012805:Sickle Cell Trait / Q000150:complications / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics; D017086:beta-Thalassemia / Q000150:complications / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics*
D006451:Hemoglobin, Sickle; D005914:Globins