Heterozygous β-thalassaemia as a susceptibility factor in mood disorders: excessive prevalence in bipolar patients

Table 1 Reduced Mean Corpuscular Volume (MCV) and Heterozygous β-Thalassaemia in 1014 Psychiatric Outpatients

RDC Diagnosis	Number of Patients	MCV<80 μ³ N (%)	Heterozygous β-Thalassaemia^a
			Definite	Probable	Total (%)
Manic Schizoaffective	288	88 (30.6)	42	16	58 (20.1)
Bipolar with Mania	269	59 (21.9)	17	21	38 (14.1)
Bipolar with Hypomania	175	36 (20.6)	16	8	24 (13.7)
Depressive Schizoaffective	96	19 (19.8)	6	4	10 (10.4)
Recurrent Major Depression	124	24 (19.4)	7	7	14 (11.3)
Other (Schizophrenia, Minor Depression, etc)	62	8 (12.9)	1	3	4 (6.5)
TOTAL	1014	234 (23.1)	89	59	148 (14.6)

^aRates of heterozygous β-thalassaemia are estimated based on the number of definite cases (MCV <80 μ³ and increased HbA₂) plus the number of probable cases (62 % of patients with MCV <80 μ³ but unknown HbA₂).