Table 1.

Inclusion and exclusion criteria in the presented study.

Inclusion Criteria (All the Following)	Exclusion Criteria (Any of the Following)
A critically ill newborn or infant in the ICU with severe unexplained neurological signs that started suddenly, but the following conditions also will be considered: metabolic failure of unknown origin; severe multi-organ disease of unknown pathogenesis, especially in case of poor responsiveness to standard treatment; severe congenital malformations that are not consistent with any known syndrome; other unexplained or unclear acute conditions.	Presence of symptoms suggesting a concrete, known genetic syndrome possible to diagnose using standard diagnostic methods (for example, Smith–Lemli–Opitz syndrome or congenital metabolic defect diagnosed in a newborn screening test performed in Poland (MS/MS, 25 inborn errors of metabolism).
	Based on pre- and perinatal history, a non-genetic etiology can explain the disease, and/or is confirmed with laboratory results/imaging techniques.
Consent form obtained from both parents for blood sampling and genetic research tests of the child and themselves.	Lack of consent form of one of the proband’s parents for blood sampling and genetic research test.