influence on the concentration of certain components. The hematocrit, which is usually unknown, is also an important factor for blood components that do not re-distribute into red blood cells. Special high sensitive assays may be required and multi-analyte measurements are preferred to get as much information of the limited samples as possible. The neonatal dried blood spots is suitable for next generation sequencing,31 DNA methylation profiling,32 metabolome profiling, vitamin D,33 multiplex measurements of cytokines,34 antibodies to infectious agents19 and whole transcriptome analysis through microarray35 and RNA-seq.36 Importantly, these measurements are made in samples drawn few days after birth, meaning that case-control differences cannot be ascribed to disease-related confounders as medication, alcohol or substance use, smoking or the disease state itself.
