Neonatal screening for haemoglobinopathy. Results in 7691 Manchester newborns

Screening for haemoglobinopathies on cord blood: laboratory and clinical experience

Objectives

Blood from the umbilical cord (cord blood) is screened for haemoglobinopathies in several neonatal screening programmes, as well as before banking as a source of stem cells. We investigated the pre-analytical and analytical aspects of neonatal screening for haemoglobinopathies on liquid cord blood using the Sebia Haemoglobin kit. We give an interpretation of the results as well as a proposed scheme for reporting of the results.

Methods

A neonatal screening programme on liquid cord blood has been performed in all labour wards in Brussels since 1994. Using that material, the screening methods of isoelectric focusing and capillary zone electrophoresis were compared using 962 cord blood samples. From December 2008 to December 2010, 47,388 neonatal samples were analysed by capillary electrophoresis as the first-line method for neonatal screening. High-performance liquid chromatography was used as the second-line method.

Results

Capillary zone electrophoresis on liquid cord blood enabled the detection of all clinically significant haemoglobin variants, significant levels of Hb Bart's, and β-thalassaemia major. Among the 47,388 neonatal samples tested, 362 (0.7%) were suspected to be contaminated with maternal blood, but no diagnostic error was reported retrospectively for a major haemoglobinopathy. Recommendations for the interpretation and reporting of results of neonatal screening for haemoglobinopathies using the Sebia Haemoglobin kit are proposed.

Conclusions

A routine capillary electrophoresis kit adapted to neonatal screening and liquid cord blood is reliable for screening for haemoglobinopathies. It enables early detection and reporting of all major haemoglobinopathies and most minor ones. It also enables use of a simple scheme to report the results.

[Neonatal detection of sickle cell disease in metropolitan France. Association française pour le dépistage et la prévention des handicaps de l'enfant (AFDPHE)]

Following the experimental program initiated in Martinique and Guadeloupe since 1983, a neonatal screening for sickle cell disease was extended to metropolitan France in 1990. It is presently applied to at risk newborns based on the parents ethnic origin, and associated with the screening for phenylketonuria, hypothyroidism and congenital adrenal hyperplaxia, in three regions. The laboratory method is reliable with a very limited number of false positive or false negative results. The cost effectiveness ratio appears very reasonable. All the children detected so far are correctly managed and have a normal development. This screening should be extended to the rest of France in the coming years.

Prediction and diagnosis of sickling disorders in neonates

A pilot scheme for the prediction and detection of sickle cell disease in neonates was set up and the results from its first three years of operation analysed. A total of 153 women booking at the antenatal clinic were found to have haemoglobin S. The protocol required that all partners of the women so identified be screened for abnormal haemoglobins and beta thalassaemia trait, and that the babies of these women should have cord blood electrophoresis performed. In fact this was only achieved in 75 partners (49%) and 91 of 145 infants (63%). Of 10 babies born with sickle cell disease during the study period, nine had mothers known to have haemoglobin S or C, but only four of these mothers' partners had been tested before delivery of the child. This pilot study highlights the problems in establishing effective antenatal screening programmes, especially in ethnic minority groups. The results show that detailed staff training, careful organisation of administrative arrangements, and education of 'at risk' groups should all be undertaken before the launching of major screening initiatives.

The epidemiology and service implications of congenital and constitutional anomalies in ethnic minorities in the United Kingdom

The literature on the incidence in the UK of congenital and constitutional anomalies in populations deriving from Africa, the Caribbean, the Far East, the Indian subcontinent and the Mediterranean is reviewed. These groups represent an increasing proportion of the whole child population. Comparison with the white population and between groups reveals that the burden of impairment varies with country of origin. Some of the reasons implicated include different gene frequencies and mating patterns, age/parity distribution and uptake of preventive services. Comparisons with prevalence at birth in the countries of origin are made where possible. In general, populations with high rates in their country of origin retain their high rates (e.g. central nervous system anomalies among births to parents deriving from the Indian subcontinent). There is a general lack of data on the prevalence of handicapping conditions such as cerebral palsy, as well as the associated health needs and service utilisation amongst ethnic minorities.

Sickle cell disease in North London

We have examined our experience of sickle cell disease in the London Borough of Haringey over the past 20 years. There are currently (1986) 145 patients on the Haringey Sickle Cell Register and when comparison is made with other centres, admission for painful crises in Hb SS disease is more frequent than in Jamaica, but the acute chest syndrome appears to be less common in the United Kingdom than in Jamaica. Splenomegaly is less frequent in Hb SC patients in this country and there is also a lower incidence of leg ulceration in both Hb SS and Hb SC disease in the United Kingdom than in Jamaica. The incidence of alloimmunization among transfused sickle cell disease individuals in Haringey is 21%, the most frequently encountered antibodies being anti-E and anti-Kell. All pregnant patients with sickle cell disease were managed with regular blood transfusion throughout pregnancy starting at 12 weeks of gestation. There were no fetal or maternal mortalities, although three babies born were 'small for dates' despite uneventful antenatal courses and adequate Hb A levels being achieved in the mother. Examination of the effect of seasonal variation on the incidence of hospital admissions for painful crises reveals no significant clustering of cases in a particular month or season of the year.

Sickle cell disease in Britain

Sickel cell disease is common in urban areas of Britain and it is estimated that in London alone there are nearly 2000 patients. One hundred and eighty four patients with sickle cell disease are known to the Central Middlesex Hospital, and 155 of those attend the sickle cell clinic regularly. The commonest cause for admission to hospital is acute painful or vaso-occlusive crisis, which accounts for 80% of all acute admissions; 12% of admissions are for acute chest syndrome. Comparison of clinical features in Brent and in Jamaica shows that the Brent patients with homozygous sickle cell anaemia are admitted with painful crises more frequently than Jamaican patients. However, the frequency of admissions for chest syndrome and priapism, and the incidence of splenomegaly are similar. Leg ulcers are uncommon in Brent. Patients with sickle cell haemoglobin C disease appeared more severely affected in Jamaica than in Brent. During the past two years 3165 newborn babies have been screened for sickle cell disease at the Central Middlesex Hospital: five babies with homozygous sickle cell anaemia and three babies with sickle cell haemoglobin C disease were detected. The overall incidence of sickle cell trait was 3.2% and of haemoglobin C trait 0.8%. A significant number of babies with sickle cell disease are born in London every year. It is essential that such babies are detected at birth and offered prophylaxis against pneumococcal infection, which is one of the major causes of infant mortality. Sickle cell disease is becoming an important blood disease in Britain and firm guidelines for the management of acute and chronic complications are required.

Screening cord blood for sickle haemoglobinopathies in Brent

Between 1981 and 1983, 3165 consecutive specimens of cord blood were tested at the Central Middlesex Hospital for the presence of an abnormal haemoglobin: the incidence of sickle cell trait was 2.8%, of HbC trait 0.9%, and the overall incidence of an abnormal haemoglobin at birth was 6.9%. Five babies with homozygous sickle cell disease, three with HbSC, and three with either HbCC or HbC beta thalassaemia were detected. Twenty two per cent of the mothers were of Afro-Caribbean origin. The cost of the test was 30p. An H6000 blood count was carried out on 1000 consecutive cord blood samples. The mean red cell volume was 97.95 (SD 3.67) fl. Thirteen cord blood samples had a mean cell volume below 85 fl, and all contained Hb Barts. In addition, six samples with a mean cell volume between 86 and 92 fl also showed Hb Barts on electrophoresis. The overall incidence of Hb Barts was 2.1%. These results indicate that the incidence of HbSS and HbSC on neonatal screening in Brent is similar to that found in the urban areas of North America and that the number may be predicted from the number of births to mothers of Afro-Caribbean origin.

Neonatal screening for sickle haemoglobinopathies in Birmingham

During 1978-81 there were about 43,500 births in Birmingham, of which 10.3% were to Negroes and 22.6% to Asians. Cellulose acetate electrophoresis of red cell haemolysates from capillary specimens collected for phenylketonuria screening was performed for these babies to assess the feasibility, cost, and benefits of detecting sickle haemoglobinopathies early. Eight babies had important haemoglobinopathies; four were homozygotes for haemoglobin S (HbS), three were mixed heterozygotes for HbS and haemoglobin C (HbC), and one had haemoglobin E (HbE) and beta-thalassemia. Also, 534 (1.19%) were heterozygotes for HbS or haemoglobin D (HbD) and 205 (0.46%) for HbC or HbE, 453 (1.01%) were heterozygotes with a fast-moving band, one was a heterozygote for haemoglobin Norfolk, and one a heterozygote for both HbS and haemoglobin G Philadelphia. The cost of neonatal screening for haemoglobinopathies was 12.5 p per baby (705 pounds for each serious abnormality).

The unreliability of mean corpuscular volume and mean cellular hemoglobin determinations in the diagnosis of alpha-thalassemia in newborn infants

Mean corpuscular volume (MCV) and mean cellular hemoglobin (MCH) were determined by means of a Hemalog 8/90 electronic counter in 51 full-term newborn infants with alpha-thalassemia-2 and 15 with alpha-thalassemia-1, as well as in 150 normal newborn infants. The mean MCV and MCH values were 92 fl +/- 06 and 33.26 pg +/- 2.22 in the normal newborn infants, 82 fl +/- 07 and 29.40 pg +/- 2.60 in the alpha-thalassemia-2 subjects, and 73 fl +/- 06 and 26.7 +/- 2.05 in the alpha-thalassemia-1 subjects. Four of the 150 normal newborn infants had MCV's < 79 fl and MCH's < 29.00 pg whereas 5 of the alpha-thalassemic subjects had MCV's > 90 fl and MCH's > 32.00 pg. We conclude that MCV and MCH determinations are unreliable in the diagnosis of alpha-thalassemia in the neonatal period.