IEM mean “inborn errors of metabolism:”- (IEMs)s often cause sudden infant death (SID ): population neonatal blood spot screening (NBS) programmes

Many inborn errors of metabolism (IEMs) may be suspected for first time as sudden infant death (SID). Nowadays, increasing numbers of neonates with IEMs (inborn errors of metabolism)  are identified pre-symptomatically by population neonatal bloodspot screening (NBS) programmes. However, some patients escape early detection because their symptoms and signs start before NBS test results become available, they even A) die even before the sample for NBS has been drawn or B) because there are IEMs which are not included in the NBS programmes. 

Since the 1990s, tandem mass spectrometry (TMS) of dried blood spots (DBS) has been developed to perform high-throughput simultaneous quantitative analysis of different diagnostic metabolites in small amounts in biological samples. As a consequence, in the last 2 decades, population neonatal bloodspot screening (NBS) programmes have expanded to include many IEMs. Patients with treatable IEMs can remain undetected by population NBS programmes for several reasons. In some IEMs, symptoms and signs including death may already occur before the NBS test results become available or even before blood for testing has been drawn, annulling the benefits of NBS.  This is especially relevant in areas where neonatal blood is collected relatively late, for instance, in fgar off rural areas .

Worldwide, across different areas, population NBS programmes differ with respect to the methodological aspects and the disorders screened.

Systematic studies on the percentage of IEMs in SID( sudden infant death syndrome)  cases are required because, although rare, SID that is preventable due to the IEM concerned being treatable does still occur.