Co-heredity of silent CAP + 1570 T>C (HBB:c*96T>C) defect and severe ß-thal mutation: a cause of mild ß-thalassemia intermedia.

INTRODUCTION: During an intensive screening program aimed at identifying the healthy carriers of thalassemia and the couples at risk of bearing an affected fetus, a rare single nucleotide variation (SNV), CAP + 1570 T > C (HBB:c*96T > C), located 12 nucleotides upstream of the polyadenylation signal in 3'UTR of the beta globin gene was identified. It was previously reported as a ß+ thalassemia mutation and later as a plain polymorphism. METHODS: Genotype identification of globin gene mutations was carried out using sequencing analysis, GAP-PCR, and MLPA methods. RESULTS: CAP + 1570 T > C (HBB:c*96T > C) was found in 39 heterozygotes, in one case in homozygous state and in thirteen cases of co-inheritance of this nucleotide substitution with other mutations in globin genes. Carriers of this mutation showed a 'silent' phenotype without appreciable microcytosis and hypochromia, so they cannot be differentiated from noncarrier individuals. Compound heterozygotes for this mutation and severe ß-thal mutations showed a variable phenotype ranging from ß-thal carrier to mild form of ß-thalassemia intermedia, revealing new aspects and allowing to better understand the clinical implications of this nucleotide substitution that can be classified as a silent ß-thalassemic defect. CONCLUSION: Data reported in this study indicate the need of investigating partner of ß-thalassemia carrier by complete sequencing analysis of ß-globin gene and of providing an appropriate genetic counseling for couples at risk undergoing prenatal diagnosis.

Incidence of haemoglobinopathies in Sicily: the impact of screening and prenatal diagnosis.

BACKGROUND: Haemoglobinopathies are a major public health problem in Sicily: it was estimated a frequency of 1/245 couples are at risk of haemoglobinopathies. This paper reviews legislative actions, prevention activities, carrier screening, genetic counselling, foetal sampling and laboratory methodology analysis evolution reporting the results of 30 years of prevention actions to assess the efficiency of our preventative programme in the control of haemoglobinopathies in Sicily. METHODS: This programme consisted principally of five phases: legislative actions, public awareness campaign, carrier screening, genetic counselling and prenatal diagnosis. RESULTS: These programmes have been very effective, which we can see from a greater public awareness of thalassaemia and its prevention in the target population furthermore by a marked decline in the incidence of thalassaemia major and sickle cell anaemia from 1 in 245 live births in the absence of prevention to 1 in 2000, with a reduction in about 85%. The residual cases were because of a conscious choice by expecting parents in relation to improved life expectancy as well as improved quality of life of the affected patients. CONCLUSION: The study suggests that public health authorities should act and invest in a similar programme for prevention of thalassaemia, as well as in relation to the increased survival of patients and the consequent organ complications.