Haemoglobin disorders: migrant health guide
Advice and guidance on the health needs of migrant patients for healthcare practitioners.
Main messages
Be alert to the possibility of haemoglobin disorders in patients from affected parts of the world.
Refer any patients diagnosed with haemoglobin disorders to specialist services for management.
Be aware that antenatal screening for haemoglobin disorders is recommended for at risk women by 10 weeks of gestation and for newborns as part of the NHS newborn Blood Spot screening programme.
Background
Haemoglobin disorders are inherited blood diseases that affect the quality or amount of haemoglobin and the capacity to carry oxygen around the body. They fall into two main categories: sickle-cell disease and thalassaemias.
WHO estimates that :
- each year over 300,000 babies with severe forms of these diseases are born worldwide, the majority in low and middle-income countries
- approximately 5% of the world’s population are carriers of a trait gene for haemoglobin disorders – mainly sickle-cell disease or thalassaemia
- as many as 25% of the population are carriers in some regions
Most carriers lead completely normal, healthy lives.
Disease can occur only when a child inherits the trait gene from both parents (autosomal recessive inheritance). These conditions are most prevalent in tropical regions; thalassaemias more common in Asia, the Mediterranean basin and the Middle East, whilst sickle cell predominates in Africa.
The main approach to the prevention of haemoglobin disorders is genetic screening and counselling.
NICE guidelines recommend antenatal screening for sickle cell diseases and/or thalassaemias for at risk women by 10 weeks of gestation.
Preconception counselling (supportive listening, advice giving and information) and carrier testing should be available to all women who are identified as being at higher risk of haemoglobin disorders, using the Family Origin Questionnaire from the NHS Antenatal and Newborn Screening Programme.
Sickle cell disease
Sickle cell disease is the most common serious genetic condition in England. One baby in every 2,000 is born with the condition and it is estimated that there are over 12,500 people with sickle cell anaemia in England.
Sickle cell disease mainly affects Black African and Black Caribbean populations. In England:
- 1 in 7 babies of Black African origin is a sickle cell carrier
- 1 in 8 babies of Black Caribbean origin is a sickle cell carrier
Sickle cell genes are also common in the following countries and regions, and in the populations that originate from them:
- Cyprus
- Greece
- Italy
- the Middle East
In sickle cell disease the haemoglobin is abnormal (HbS). It leads to misshapen red blood cells, which:
- lack plasticity and so can cause blockages in small blood vessels
- have a reduced lifespan
This can lead to:
- anaemia
- acute painful ‘crises’
- severe bacterial infections eg pneumonia
- tissue death (necrosis)
Diagnosis is on the basis of history and blood examination; low haemoglobin, usually around 6-8 g/dl, with normochromic normocytic anaemia, high reticulocytes around 20% and sickle cells present in the blood film.
The diagnosis is confirmed by identification of HbS by electrophoresis.
Patients diagnosed with sickle-cell disease should be referred to specialist services for management. In addition baseline assessment of renal, liver and lung function should be undertaken at diagnosis. Further investigation depends upon complications.
The condition can sometimes be cured by bone marrow transplant if there is a suitable donor. This only happens in about 1 in 10 cases.
Management is based on avoiding factors that may precipitate a crisis through:
- good fluid intake - increased in crises
- healthy diet with folic acid supplementation (especially during pregnancy). Note that Vitamin D deficiency may co-exist and zinc should be considered if growth is restricted
- prophylactic penicillin and pneumococcal vaccination
- surveillance and prompt use of antibiotics for infections
- prevention of vascular stasis and avoidance of the cold especially during a crises
While sickle cell trait confers some protection against malaria, antimalarials should still be taken if travelling to a malaria risk country.
Those with sickle cell disease are very susceptible to severe malaria and travel to malaria risk areas should be discouraged.
Renal and liver function should be taken into consideration before prescribing anti-malarials.
Specialist treatment including possible admission is required when painful or other crises occur.
Thalassaemias
The thalassaemias are a group of genetic disorders characterised by a decreased or absence of synthesis of polypeptide chains that form normal haemoglobin.
There are 2 major types of thalassaemia; named for the 2 protein chains that make up normal haemoglobin: alpha and beta.
Both alpha and beta thalassaemias:
- lead to variable production of abnormal haemoglobin and,
- have both mild and severe forms.
Beta thalassaemia major is the most common and severe form of the condition in the UK.
In England approximately 1,000 people are affected by thalassaemia with around 214,000 carriers. The highest prevalence of thalassaemia is found in Bangladeshi, Chinese, Cypriot, Indian and Pakistani communities.
People with more severe types of thalassemia (beta major) are not able to make enough haemoglobin, which means that oxygen cannot get to all parts of the body. Organs then become starved of oxygen and are unable to function properly. This usually presents in childhood starting around 3 months of age. If not treated children are affected by its complications such as:
- growth retardation
- poor muscular development
- tendency to pathological fractures and frontal bossing with maxillary prominence.
- liver, spleen and gland damage
- bone deformities
Beta thalassemia intermedia present later in life with milder symptoms.
Symptoms include:
- fatigue
- weakness
- shortness of breath
- jaundice
- anaemia
Diagnosis is by history and blood test (hypochromic microcytic anaemia) with confirmation by haemoglobin electrophoresis.
Patients diagnosed with thalassaemia should be referred to specialist services for management.
Treatment of severe disease is mainly by regular blood transfusions to maintain haemoglobin levels.
Secondary treatment is also required to manage iron overload resulting from multiple transfusions.
Thalassaemias can sometimes be cured by bone-marrow transplantation where a suitable donor exists.
Resources
NHS leaflets and factsheets about sickle cell, thalassaemia and screening
Information on the NHS programme of antenatal screening for haemoglobin disorders - available in a range of languages
NHS specialised haemoglobinopathy services
The Sickle Cell Society - information and care for those with sickle cell and their families