July 25, 2022
Inborn errors of metabolism are a spectrum of rare disorders which manifest in neonates and early childhood.
A disease or disorder is rare when it affects less than 1 in 2500 individuals. World Health Organization (WHO) defines a rare disease as often debilitating lifelong illness or disorder with a prevalence of 1 or less per 1000 populations. The total number of people with a rare disease is estimated to be approximately 300 million worldwide and 72% of rare diseases are genetic out of which 70% start in childhood.
Inborn errors of metabolism are a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are defects of single genes that code for enzymes that facilitate the conversion of various substances (substrates) into others (products). In most disorders, problems arise due to the accumulation of toxic substances, or interferences with normal functioning, or reduced ability to synthesize essential compounds. Inborn errors of metabolism are now often referred to as congenital metabolic diseases or inherited metabolic disorders.
There are more than 500 inherited metabolic diseases known today. Traditionally, inherited metabolic diseases were classified as disorders of carbohydrate metabolism, amino acid metabolism, organic acid metabolism, or lysosomal storage diseases.
Early diagnosis of rare diseases is a challenge due to multiple factors, including lack of awareness among the public (even among healthcare providers), low accessibility to healthcare facilities, and inadequate screening and diagnostic facilities. Hence, most of the inborn errors of metabolism cases are diagnosed very late (after life-threatening or irreversible damage has been done) or remain even undiagnosed and result in unexplained neonatal/ infant deaths or permanent deficits.
Symptoms: The common symptoms involve unintended weight loss, or a failure to gain weight, tiredness and lack of energy, hypoglycaemia or low blood sugar, poor feeding habits, stomach problems or vomiting, high levels of acid or ammonia in the blood, abnormal liver function, developmental delays, mental retardation in babies and children, and convulsions.
Few of the disorders can be picked up early through Newborn screening.
What is newborn screening?
This kind of blood test is performed to detect inherited metabolic/genetic disorders. The newborn screening usually includes a panel of tests that screen for inborn metabolic/genetic disorders most common or prevalent in a particular geographical area. If symptomatically or clinically indicated, screening for other geographically rarely identified disorders are also carried out based on the requirement of a particular baby, however, the routine newborn screening does not cover these extremely rarely identified spectrum of disorders.
Example to this list is congenital hypothyroidism, most prevalent endocrine disorder. If we detect this at birth through one drop of blood by heel prick we can prevent the mental retardation in vulnerable groups.
Why newborn screening must be done?
To detect disorders before symptoms appear and to treat and prevent long term and irreversible neurological and developmental damages.
Newborn screening panel in Kasturba Hospital, Manipal
The newborn screening panel of Kasturba Hospital, Manipal, screens for commonly picked up IEMs of Karavali region which includes Congenital Hypothyroidism, Congenital Adrenal Hyperplasia (CAH), Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency, Galactosemia, Phenylketonuria, Biotinidase Deficiency, Maple Syrup Urine Disease (MSUD) in neonatal blood.
How is newborn screening done?
• Using a few drops of blood from baby’s heel on special paper
• Ideal time to screen is 48-72 hours
What is done if the Newborn screen result is positive?
If a baby shows positive test results for any of the disorders screened in newborn screening, immediate precautionary measures are instituted to prevent damage and additional confirmatory tests are carried out to confirm the diagnosis.
What are the Treatment options available for these IEMs?
Treatment for metabolic disorders depends on the specific condition. Common treatments include:
• Changes to diet and lifestyle: Avoid certain foods that the body cannot handle and break down.
• Medicines: Medicines may be used to control specific symptoms, help feel better, and avoid life-threatening emergencies.
• Enzyme replacement therapy: Injections of a missing or low enzyme may help treat specific disorders.
A healthy newborn is every parent’s dream as well as the pillar of our future. Ensuring each new-born overall well-being by screening for rarely identified metabolic diseases is crucial to secure their health and provide each of them with the best possible quality of life (irrespective of the IMDs afflicting them). However, a lot remains to be done in this area in terms of raising awareness among the parents and primary caregivers of the baby, accessibility to medical screening facilities, affordability of the screening, and confirmatory tests, therapeutic approaches, destigmatization of the society toward “special child” and appropriate counselling to ensure regular follow up and compliance to treatment. Healthcare has made huge progress in the last few decades. We would surely achieve our goal of “screening, securing and offering the best possible care to every neonate” which is the concerted efforts of all the stakeholders.
We once again emphasise the importance of getting every new-born screened for geographically prevalent IEMs at birth because after all “Each baby, each life is precious”.
For Feedback and queries, please send an email to: marketing.kh@manipal.edu or call +91 820 2922686.
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