RNA sequencing of archived dried blood spots

Neonatal dried blood spots (DBS) are routinely collected on standard Guthrie cards for all-comprising national newborn screening programs for inborn errors of metabolism, hypothyroidism and other diseases. In Denmark, the Guthrie cards are stored at – 20 °C in the Danish Neonatal Screening Biobank and each sample is linked to elaborate social and medical registries. This provides a unique biospecimen repository to enable large population research at a perinatal level.

Here, researchers from the Lundbeck Foundation Initiative for Integrative Psychiatric Research demonstrate the feasibility to obtain gene expression data from DBS using next-generation RNA sequencing (RNA-seq). RNA-seq was performed on five males and five females. Sequencing results have an average of > 30 million reads per sample. 26,799 annotated features can be identified with 64% features detectable without fragments per kilobase of transcript per million mapped reads (FPKM) cutoff; number of detectable features dropped to 18% when FPKM ≥ 1. Sex can be discriminated using blood-based sex-specific gene set identified by the Genotype-Tissue Expression consortium.

 Hierarchical clustering (HC) and heat maps (HM) based on
a gene set enrichment of hemoglobin species

A) HC of all the identified blood genes. B) HM of all the identified blood genes. C) HC of the identified blood genes, excluding HBA1. D) HM of all the identified blood genes, excluding HBA1. E) HC based on the entire gene set (unfiltered).