Types of services required for the prevention and care of congenital disorders and genetic diseases at different health-care levels
Before addressing the services according to level of care, it is appropriate to discuss the nature of services according to prevention strategies, i.e. primary, secondary and tertiary prevention.
The goal of primary prevention is to reduce the incidence of congenital disorders and genetic diseases through the removal of causative factors. The majority of identified causes of congenital disorders are non-hereditary and the main primary prevention measures include the following:
- Expansion of rubella immunization: The implementation of immunization programmes are a function of political will expressed as appropriate funding and a minimum of infrastructure, cold chains and adequate organization at community levels. In Latin America and the Caribbean, the WHO Pan American Sanitary Bureau has been promoting rubella vaccination as part of childhood immunization since the late 1990’s. Eradication of congenital rubella syndrome is within reach in Latin America and the Caribbean by the end of this
- Folic acid fortification: Pre-conception multivitamin intake reduces the risk of neural tube defects in the offspring, and the key protective factor is folic acid. Many LMIC have instituted folic acid fortification of main staples, and abundant data confirm the beneficial effect in reducing neural tube defects by at least 50%. Beneficial effects in the prevention of other congenital and adult conditions are being
- Pre-conception care and family planning: Pre-conception care is known to improve pregnancy outcome. Family planning is a basic human right of women and has a positive role in reproductive health and the improvement of pregnancy, including a decline in birth prevalence of congenital disorders. Genetic components of pre- conception care include: detection of genetic risks through family history; addressing the issue of consanguinity if relevant; explaining programmes of prevention of congenital disorders and genetic diseases that exist in the community; and genetics counselling as
- Adequate prenatal care: Prenatal care includes nutrition and control of maternal infections and other
- Avoidance of potential teratogens in pregnancy: Traditions, socioeconomic factors and medical culture make it difficult to avoid exposure to teratogens. Certain cultures in developing countries resort to home remedies of unknown composition and teratogenic potential. Moreover, in some developing countries pharmaceutical companies market their products directly to consumers, who can purchase and consume most medications without medical prescription, even during pregnancy. Compounding these factors, environmental quality regulations tend to be lax and pregnant women are commonly exposed to environmental pollutants. Avoidance of teratogens, including smoking, alcohol intake and unwarranted medications, should be recommended. Teratogen information services are a valid strategy to prevent exposure to known teratogens.
Prevention based on reproductive options
The limitations and difficulties of primary prevention programmes for congenital disorders have led to the implementation of prevention by reproduction options, in which couples at risk are detected and offered voluntary options to avoid having an affected child. This approach includes:
- Detection of heterozygotes (carriers) for autosomal recessive conditions: These may be particularly prevalent and severe in a community. The purpose of carrier-testing in this context is to help couples at risk plan their reproduction to avoid having an affected child. Carrier-testing for reproductive purposes may be voluntary or mandated by law (for example premarital testing for thalassaemia in Cyprus and Iran), depending on the country. When both spouses are carriers, community genetics services should offer voluntary genetic counselling on the reproductive options available to avoid affected offspring. These options should be voluntary and devoid of coercion of any kind, and generally include (a) not marrying (if detection is premarital), (b) abstaining from reproduction, (c) running the genetic risk, or (d) availing to prenatal diagnosis, followed by the option of continuing or interrupting an affected pregnancy, depending on the legislation on abortion. The reproductive options approach has a number of ethical nuances – it must be voluntary, and it requires social consensus, organization and resources. Prime examples include the thalassaemia prevention programmes in Cyprus, Greece, Italy, Iran and other countries (Angastiniotis & Hadjiminas, 1981; Samavat & Modell, 2004; Ayesh et al., 2005; Elgawhary et al., 2008), and the prevention of recessive diseases common in Ashkenazi Jews worldwide (Kaback, 2000).
- Non-invasive prenatal screening for Down syndrome: This can be followed by prenatal diagnosis in positive screens if desired by the
- Genetics reproductive services (genetic counselling, prenatal diagnosis): These can be adopted for other genetic diseases according to their burden in the
- Presymptomatic diagnosis of autosomal dominant conditions of late onset: Diagnosis can be followed by the same reproductive options mentioned above. This approach also must be voluntary due to a number of ethical and psychosocial issues. There are many examples of such prevention programmes when the condition is severe, has no treatment, and is highly prevalent in a community, for example, spinocerebellar atrophy in Holguín, Cuba, and Huntington disease in Lake Maracaibo,
Secondary prevention (early diagnosis and treatment to avoid complications)
- Newborn screening: This is the prime example of secondary prevention of congenital disorders. There are a number of requisites and conditions for its effective implementation, including the selection of conditions to screen for, the organizational aspects, cost/benefit considerations, follow-up of initial positives, treatment of confirmed positives,
- Predictive genetic testing: For conditions in which there are proven and cost-effective preventive or therapeutic interventions on those who test
- Follow-up of children: For children with congenital disorders and genetic diseases with the strategy of anticipatory guidance and interventions to prevent complications and improve quality of life (e.g. haemoglobinopathies, deafness).
Tertiary prevention (surgical repair and rehabilitation)
- Surgical treatment of congenital defects: For defects such as congenital heart defects, cleft lip and palate, neural tube
- Rehabilitation programmes: For learning disabilities, cognitive impairment, musculoskeletal and other
Commitment of policy-makers
Political will and commitment is needed for funding, planning and managing the care and prevention initiatives. It is important to form a national committee addressing the care and prevention of congenital disorders that collaborates closely with WHO country and regional offices. Policy-makers become more aware of the health burden of congenital disorders when reliable data on prevalence and burden of congenital disorders become available.
Epidemiological studies on frequency of the disorders and their impact on public health and social life should therefore be conducted without delay. Morbidity and mortality burden data are needed. Decisions need to be made on whether genetics services should be comprehensive or start with specific priorities dictated by local needs and available resources. Priorities are defined by carrying out standardized epidemiological surveys and collecting demographic data, to identify the principal national problems related to congenital disorders, and to clarify the situation on the availability, extent and quality of genetics services.
Planned prevention programmes, besides being cost-effective, should take into consideration local beliefs and social attitudes. For example, premarital screening and pre-conception counselling as preventive measures are more acceptable than terminations of affected pregnancies in many countries where the latter is not acceptable.
Epidemiological studies should address the following:
- data on the prevalence and burden of congenital disorders in the country;
- data on available genetics services, both clinical and diagnostic laboratory services;
- data on available human resources in clinical genetics and genetics laboratory personnel;
- data on number and capacities of special schools for the care and rehabilitation of affected;
- data on college curricula related to genetics and genetics
Integration of community genetics services into the primary health-care system
Integration of community genetics services into existing health-care systems can be feasibly implemented in most low- and middle-income countries (Penchaszadeh, 2000; Alwan & Modell, 2003; Christianson & Modell, 2004; Qureshi et al., 2004). The establishment of vertical programmes is hard to implement with a high demand for sustainable funds and human resources. Integration of public health approaches into the existing primary care and reproductive health clinics is probably the most appropriate, sustainable and cost-effective approach. Although some additional training and resources will be required, the potential benefits are considerable (Hamamy & Bittles, 2009).
An example of the integration of community genetics services into primary health-care programmes is the inclusion of pre-conception and post-conception counselling and screening in reproductive health clinics. The approach includes pre-conception information and risk detection (nutrition, maternal infections, Rh status, parental age, maternal disease, teratogenic drugs and chemicals, counselling for consanguinity), referral of couples at high genetic risk to specialized centres, carrier screening and newborn screening programmes, and care for the affected individuals and their families. Community genetics services in secondary and tertiary care would include the provision of specialist genetics counselling for high-risk families and care for the affected.
Registries of congenital disorders and genetic diseases
The expected benefits of registries are to determine the baseline birth prevalence of each type of congenital disorder, to increase awareness within the medical community of these conditions, and to improve the quality of diagnosis and recording (Rajab, Patton & Modell, 2000; Al Hosani et al., 2005). The aim is to establish a priority list of preventive measures and help organize better care for patients with special needs, for example those with Down syndrome. In addition, the register can have a surveillance function for the identification of significant changes in the baseline rate for specific congenital disorders, which may indicate the existence of particular personal or demographic factors.
Certain requirements need to be addressed in initiating genetics registries. These include:
- selecting the conditions that should be initially registered;
- performing personnel training;
- defining responsibilities;
- recruiting experts for planning and implementing the registry;
- providing training for physicians and nurses on examination of newborns to detect congenital
A problem that can face the implementation of a national registry is the reluctance of health-care personnel to complete the registry forms, which requires their time and effort. Incentives to encourage this are important to consider in low- and middle-income countries.
Population screening programmes
Population screening involves the following programmes:
- Newborn screening: Newborn screening, the “dean” of genetic screening programmes, has been applied on very large and systematic scale for the past 40 years, both in high- income countries and in some low- and middle-income countries (Al Hosani et al., 2005; Khandekar et al., 2006; Al Arrayed et al., 2007; Saadallah & Rashed, 2007). Newborn screening began in developed nations in the 1960s with screening for phenylketonuria, followed soon after by screening for congenital hypothyroidism. There are a number of prerequisites for the development and implementation of newborn screening (WHO 2006a). Newborn screening programmes vary in different countries according to the prevalence of specific conditions:
- All countries that conduct newborn screening, screen for congenital hypothyroidism, which is one of the most common preventable causes of mental retardation worldwide (Rose et al., 2006; Jain et al., 2008).
- Some countries with a large proportion of the population being of European descent, test also for phenylketonuria and cystic
- Some countries with a large proportion of the population being of African, Mediterranean or Asian descent conduct newborn screening for genetic blood disorders which benefit from early detection and management, such as sickle cell anaemia and G6PD deficiency (Al Arrayed et al., 2007).
Newborn screening for congenital hypothyroidism should be introduced in all low- and middle-income countries, irrespective of the economic status, as a robust preventive measure of mental retardation.
- Carrier screening: Carrier screening, used among healthy people, detects those who are heterozygote for recessive genes particularly prevalent in the community. The goal of these programmes is to expand the reproductive options of carrier individuals. These options should always be voluntary and could include: (a) avoid marrying someone who is also a carrier; (b) opt for prenatal diagnosis of the disorder in question (e.g. thalassaemia), followed by voluntary termination of affected pregnancies. The combination of these interventions has reduced the prevalence of thalassaemia by more than 90% in Cyprus, with significant reduction also in Greece, Italy, Bahrain and Iran, among others (Al Arrayed, 1997; Angastiniotis & Hadjiminas, 1981; Al-Arrayed et al., 2003; Samavat & Modell, 2004).
- Prenatal screening: Prenatal screening detects chromosome abnormalities such as Down syndrome, neural tube defects and major fetal malformations, as well as haemoglobinopathies. This is conducted by ultrasound and biochemical assays in maternal blood. Few countries have explicit prenatal screening policies, although such interventions are standards of obstetrical practice in most developed countries and in limited scale (usually restricted to the high-income groups) in all countries. The obvious aim of these interventions is to allow couples to decide whether or not they wish to pursue an affected pregnancy. Thus, these services are recommended particularly when the voluntary option to terminate an affected pregnancy is available and accessible (Chaabouni et al., 2001).
Genetics centres and introduction of new technology
The molecular revolution that characterized the last three decades has introduced into medical practice many procedures that aid the diagnosis and prevention of congenital disorders. Such technologies can be introduced gradually into a country’s care and prevention programmes of congenital disorders, according to their proven validity and utility as well as their cost and effectiveness. Intercountry collaboration programmes should be stimulated.
Improving care and rehabilitation for those affected with congenital disorders
Several efficient care and rehabilitation management procedures exist for those affected with congenital disorders, including surgery for congenital malformations, dietary therapy for some metabolic disorders and rehabilitation for those with mental and physical disabilities. Haemoglobinopathies are amenable to efficient management and good prognosis despite the difficulties. For example, thalassaemia is a significant issue for medical centres throughout the world because of the constant demand for blood transfusions and for self-administered iron chelation therapy. When thalassaemia was first described, the prognosis for patients was poor because the condition was incompatible with life. However, continuous blood transfusions and iron chelation therapy led patients with thalassaemia to have a normal lifespan, provided they comply with their therapy. Because patients face the burden of a chronic illness, psychosocial problems are common (Gharaibeh, Amarneh & Zamzam, 2009), as are the psychological issues that interfere with compliance to ongoing therapy (Musallam, Cappellini & Taher, 2008). The proportion of patients administering desferrioxamine at least four days per week in Egypt and Iran was just below 60% and in Jordan, around 75%. The most frequently reported category of reasons for patients missing a dose related to their beliefs and feelings about the treatment (Ward et al., 2002). Furthermore, severe complications related to the repeated blood transfusions in thalassaemic patients still exist, such as life-threatening heart disease as a consequence of iron overload (Caro et al., 2002; Al-Hawsawi et al., 2003; Inati et al., 2006; Charafeddine et al., 2008). Other serious complications related to thalassaemia include the risk of hepatitis C in thalassaemic patients (Al-Fuzae, Aboolbacker & Al Saleh, 1998), and the occurrence of thromboembolic events (Taher et al., 2006).
Health systems are organized by level of care. Primary care is both a comprehensive approach to health care, with components of prevention and treatment, as well as the port of entry of the population to the health system. Secondary and tertiary levels of care deal increasingly with complex health issues. At these levels therapeutic medicine and high technology are more developed. In all countries, and particularly in LMIC, the bulk of health care occurs at primary- care level. Accordingly, community genetics actions must have an emphasis in primary care.
Community genetics in primary health care
The following are community genetics services that should be available in the primary health-care level:
- use of family history as a strategy to detect genetic risk factors;
- clinical suspicion, at all ages, of disorders that could be caused by genetic factors, followed by appropriate referrals to secondary and tertiary levels of care;
- follow-up of results of newborn screening and referrals of presumed positives to higher level centres;
- pre-conception counselling and care in reproductive health clinics , including avoidance of alcohol, smoking and teratogens, family planning and discussion of genetic and environmental risks;
- detection of heterozygotes for a particular recessive condition when that is part of a prevention programme in the community;
- presymptomatic diagnosis and genetic counselling of late-onset, single-gene disorders when that is part of a prevention programme in the community (e.g. Huntington’s disease in Lake of Maracaibo, Venezuela, and spinocerebellar atrophy in the province of Holguin, Cuba);
- genetic counselling in low complexity situations or as part of a particular prevention programme (e.g. thalassaemia, sickle-cell disease, spinocerebellar atrophy);
- prenatal care including counselling on avoidance of exposures to teratogens and ultrasound in gestation for the detection of fetal
As recommended for all health services provided at primary-care level, guidelines for referrals to higher levels of care should be available also for genetic conditions and congenital anomalies.
Community genetics in secondary and tertiary health-care levels
Community genetics in these health-care levels include the following:
- supervision of services provided in the primary-care level;
- clinical genetics diagnostic services;
- genetic counselling;
- genetic testing for diagnosis: cytogenetic, DNA testing;
- prenatal diagnosis;
- predictive testing;
- education to health professionals, policy-makers, the
Education in genetics
Education in genetics should be provided to all health professionals, policy-makers, and the public and needs to include topics such as: consanguinity; prenatal and newborn screening and detection of signs of possible genetic conditions common in the area; prevention and care programmes that take place in the community; and ethical, legal and social issues. Education in genetics is required to implement efficiently community genetics services in primary health care.