Bernadette Modell

Global epidemiology of haemoglobin disorders and derived service indicators

To demonstrate a method for using genetic epidemiological data to assess the needs for equitable and cost-effective services for the treatment and prevention of haemoglobin disorders. We obtained data on demographics and prevalence of gene variants responsible for haemoglobin disorders from online databases, reference resources, and published articles. A global epidemiological database for haemoglobin disorders by country was established, including five practical service indicators to express the needs for care (indicator 1) and prevention (indicators 2-5). Haemoglobin disorders present a significant health problem in 71% of 229 countries, and these 71% of countries include 89% of all births worldwide. Over 330,000 affected infants are born annually (83% sickle cell disorders, 17% thalassaemias). Haemoglobin disorders account for about 3.4% of deaths in children less than 5 years of age. Globally, around 7% of pregnant women carry b or a zero thalassaemia, or haemoglobin S, C, D Punjab or E, and over 1% of couples are at risk. Carriers and at-risk couples should be informed of their risk and the options for reducing it. Screening for haemoglobin disorders should form part of basic health services in most countries.

Survival in β-thalassaemia major in the UK: data from the UK Thalassaemia Register

About 50% of UK patients with beta-thalassaemia major die before the age of 35 years, mainly because conventional iron-chelation therapy is too burdensome for full adherence. Patients require an individually-tailored treatment plan incorporating new, more tolerable approaches.

Improved survival of thalassaemia major in the UK and relation to T2* cardiovascular magnetic resonance

BackgroundThe UK Thalassaemia Register records births, deaths and selected clinical data of patients with thalassaemia who are resident in the UK. A study of survival and causes of death was undertaken which aimed to include the possible impact of T2* cardiovascular magnetic resonance (CMR).MethodsThe Register was updated to the end of 2003, copies of death certificates were obtained, and causes of death in beta thalassaemia major were extracted. In addition, patients who had T2* CMR assessment of cardiac iron load and/or received the oral iron chelator deferiprone were identified from clinical records.ResultsThe main causes of death were anaemia (before 1980), infections, complications of bone marrow transplantation and cardiac disease due to iron overload. From 1980 to 1999 there were 12.7 deaths from all causes per 1,000 patient years. Forty per cent of patients born before 1980 had T2* cardiovascular magnetic resonance between 2000 and 2003, and 36% of these patients were prescribed deferiprone before end of 2003. In 2000–2003, the death rate from all causes fell significantly to 4.3 per 1,000 patient years (-62%, p < 0.05). This was mainly driven by the reduction in the rate of deaths from iron overload which fell from 7.9 to 2.3 deaths per 1,000 patient years (-71%, p < 0.05).ConclusionSince 1999, there has been a marked improvement in survival in thalassaemia major in the UK, which has been mainly driven by a reduction in deaths due to cardiac iron overload. The most likely causes for this include the introduction of T2* CMR to identify myocardial siderosis and appropriate intensification of iron chelation treatment, alongside other improvements in clinical care.

Global Epidemiology of Hemoglobin Disorders

Abstract: Thalassemias and the hemoglobinopathies such as Hemoglobins S, C and E, are now a global problem. They have spread through migration from their native areas in the Mediterranean, Africa and Asia and are now endemic throughout Europe, the Americas and Australia. Comprehensive control programs in recent years have succeeded in limiting the numbers of new births and prolonging life in affected individuals. Such programs have been successful in a minority of countries and have little global impact. Over 300,000 infants with major syndromes are born every year and the majority die undiagnosed, untreated or under‐treated.

Iranian national thalassaemia screening programme

Irans experience shows that genetic screening can be successful in lower resource countries and also provides some lessons for high resource nations

Genetic counselling and customary consanguineous marriage

Consanguineous marriage is customary in many societies, but leads to an increased birth prevalence of infants with severe recessive disorders. It is therefore often proposed that consanguineous marriage should be discouraged on medical grounds. However, several expert groups have pointed out that this proposal is inconsistent with the ethical principles of genetic counselling, overlooks the social importance of consanguineous marriage and is ineffective. Instead, they suggest that the custom increases the possibilities for effective genetic counselling, and recommend a concerted effort to identify families at increased risk, and to provide them with risk information and carrier testing when feasible.

Method of sampling chorionic villi in first trimester of pregnancy under guidance of real time ultrasound.

Samples of chorionic villi were obtained in the first trimester by aspiration using a cannula passed transcervically under the guidance of real time ultrasound. In initial studies in 47 anaesthetised patients immediately before therapeutic abortion a method was developed giving a success rate of 89%. In 10 patients successful sampling was performed as an outpatient procedure without anaesthesia. In all, seven diagnostic procedures were undertaken and four of the five unaffected pregnancies continued. The technique of chorionic villous sampling using real time ultrasound is simple to learn and yields material for biochemical analysis and chromosomal study without the need for tissue culture. The exact obstetric risk, however, remains to be defined.

Association of thalassaemia intermedia with a beta-globin gene haplotype

We have identified 14 Asian patients with homozygous β° thalassaemia who had a mild clinical disorder related to an augmented production of haemoglobin F. None of their parents had an elevated level of Hb F. Restriction fragment length polymorphism analysis of the β‐globin cluster of these patients and a control group of Asian thalassaemia major patients showed that 6/14 of the thalassaemia intermedia patients were homozgyous for a particular 5′β‐globin haplotype (−+−++), in contrast to 1/42 of the thalassaemia major patients. Furthermore, the —+—++β haplotype is also associated with amelioration of disease severity in β thalassaemia in an Italian population. This β haplotype is linked to a DNA sequence variation 5′ (at position — 158) to the cγ globin gene which can be detected by the presence (+) of an Xmn I restriction enzyme site. The possible role of the Xmn I‐γ polymorphism in relation to this variant HPFH is discussed. We conclude that much of the observed clinical variability of β thalassaemia can now be explained by the inheritance of β thalassaemia chromosomes with different propensities for fetal haemoglobin production.

Informed choice in genetic screening for thalassaemia during pregnancy: audit from a national confidential inquiry.

Abstract Objective: National audit of informed choice in antenatal screening for thalassaemia. Design: Audit from the UK Confidential Enquiry into Counselling for Genetic Disorders. Setting: Thalassaemia module of the UK Confidential Enquiry into Counselling for Genetic Disorders. Subjects: 138 of 156 couples who had had a pregnancy affected by a major β thalassaemia from 1990 to 1994. Main outcome measures: How and when genetic risk was identified for each couple, and whether and when prenatal diagnosis was offered. Results: Risk was detected by screening before or during the first pregnancy in 49% (68/138) of couples and by diagnosis of an affected child in 28% (38/138) of couples. Prenatal diagnosis was offered in 69% (274/400) of pregnancies, ranging from 94% (122/130) for British Cypriots to 54% (80/149) for British Pakistanis and from 90% in the south east of England to 39% in the West Midlands. Uptake of prenatal diagnosis was 80% (216/274), ranging from 98% (117/120) among British Cypriots in either the first or second trimester to 73% (35/48) among British Pakistanis in the first trimester and 39% (11/28) in the second trimester. A demonstrable service failure occurred in 28% (110/400) of pregnancies, including 110 of 126 where prenatal diagnosis was not offered and 48 of 93 that ended with an affected liveborn infant. Conclusion: Although antenatal screening and counselling for haemoglobin disorders are standard practices in the United Kingdom, they are delivered inadequately and inequitably. An explicit national policy is needed, aiming to make prenatal diagnosis in the first trimester available to all couples and including ongoing national audit.

Recommendations for introducing genetics services in developing countries

Many concerned scientists believe that developments in the medical application of genomics will widen the gap between the developed and the developing world. We argue that most developing countries now urgently need to incorporate genetic approaches (including DNA diagnosis) into their health services, and that many are able to do so. DNA diagnosis is relatively inexpensive, helps to develop skills in molecular biology and provides a basis for developing national expertise in genomics.