Factors regulating Hb F synthesis in thalassemic diseases

BMC Hematology

Table 4 Distribution of beta thal alleles in beta thal int and thal major patients.

Type of thalassemic disease	N. cases	n. of identified alleles	Alleles beta thal silent	Alleles beta+ thal mild	Alleles beta+ thal severe and beta ° thal
Sub-silent thal int	33	61	22 (37%)	8 (13%)	31 (50%)
Evident thal int	41	81	9 (12%)	36 (44%)	36 (44%)
beta thal int in double heterozygous beta thal + triplicated alpha	58	100	0	0	100 (100%)
Thal major	24	47	1 (2.1%)	7 (15%)	39 (83%)

The silent, mild, severe beta-thal defects present in Italy are: 1. Silent: -101 C→T; -92 C→T; IVS II-844 C→G; triplicated alpha^{anti 3.7}; triplicated alpha^{anti 4.2}: ; they have a hematologic-hemoglobinic picture completely normal or with some mild thal characters. 2. mild or sub-silent: -87 C→G or C→T; -86 C→G or C→A; IVS-1 6 T→C that have a constant but very mild thal hematologic picture and a mild increase of Hb A₂. 3. severe: beta°39 C→T; IVS 1–110 G→A; IVS II-745 C→G; frameshift 6 (-A) that have all very marked hematologic and hemoglobinic characters.

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