APRIL 22 — As Malaysia joins the global community in observing World Primary Immunodeficiency Week from April 22 to 29, 2026, attention turns to a group of conditions that are often described as rare, but are more accurately understood as rarely recognised.These disorders, now classified as Inborn Errors of Immunity (IEI), encompass more than 500 genetically defined conditions that impair the body’s ability to defend itself against infections. At a clinical level, they are defects in the body’s genetic blueprint. At a human level, they are often a quiet and prolonged struggle, marked by repeated illness, delayed diagnosis, and uncertainty.In Malaysia, this struggle is compounded by a significant diagnostic gap.
A systematic review conducted in 2020 reported a prevalence of only 0.37 cases per 100,000 people. When compared to international registry data, this figure is strikingly low. Current estimates suggest that between 70 per cent and 90 per cent of Malaysians living with these conditions remain undiagnosed.This is not simply a matter of rarity.
It is a matter of visibility.Children born with severe forms of immune deficiency may appear entirely healthy in their earliest days. One such condition, Severe Combined Immunodeficiency (SCID), is characterised by the absence of functional T and B lymphocytes, leaving infants highly vulnerable to infections. Without early detection, these children often experience recurrent pneumonia, persistent infections, and failure to thrive before a diagnosis is eventually made, sometimes after irreversible complications have occurred.
Children can appear healthy at first, but hidden immune disorders often mean a quiet, prolonged struggle marked by repeated illness and delayed diagnosis. — Unsplash pic for illustration only The challenge, therefore, is not only clinical but systemic. Delayed diagnosis is frequently linked to gaps in awareness, both among the public and within the healthcare system itself. A recent study conducted at USM, published in the Malaysian Journal of Medicine and Health Sciences, examined the knowledge, attitudes, and practices of medical practitioners regarding expanded newborn screening.
The findings pointed to a notable gap in awareness, particularly in relation to the implementation and benefits of such screening programmes.When early signs are not recognised, opportunities for timely intervention are lost. Recurrent ear or sinus infections, prolonged courses of antibiotics with limited effect, poor weight gain in infants, and repeated hospital admissions for infections may appear as isolated clinical events. Taken together, however, they can form a pattern that warrants further investigation.
Recognising these patterns is often the first step towards diagnosis.Encouragingly, Malaysia has taken an important step forward with the launch of the National Policy for Rare Diseases in February 2026. The policy signals a commitment to strengthening clinical governance, improving early detection, and integrating rare diseases into the broader healthcare agenda. It provides a timely opportunity to address long-standing gaps in diagnosis and care.One of the most critical areas for improvement lies in newborn screening.
At present, there is limited published evidence on systematic screening for primary immunodeficiencies in Malaysia. Yet for conditions such as SCID, early identification through newborn screening can be life-saving. Detecting the disorder before infections occur allows for timely interventions, including curative treatment options.Advances in diagnostic technology have also made early detection more feasible.
Techniques such as whole exome sequencing and targeted genetic panels enable clinicians to identify specific mutations responsible for immune dysfunction. In parallel, laboratory tests such as TBNK flow cytometry can rapidly assess key immune cell populations, guiding clinical decision-making.Importantly, treatment is not beyond reach. Intravenous immunoglobulin therapy, which replaces missing antibodies, is already available and subsidised in public healthcare settings for patients with antibody deficiencies.
For more severe cases, hematopoietic stem cell transplantation offers a potential cure, with success rates exceeding 90 per cent when performed early.These developments highlight an important reality. For many patients with immune disorders, the barrier is not the absence of treatment, but the delay in diagnosis.Addressing this requires a coordinated approach. Expanding newborn screening programmes would allow conditions such as SCID to be detected at birth.
Strengthening training for healthcare providers can help bridge existing knowledge gaps and improve clinical suspicion. Increasing access to specialised care, including clinical immunology services in regional hospitals, would ensure that patients receive timely and appropriate management.At the same time, public awareness remains essential. Families are often the first to no