Individuals with severe combined immunodeficiency (SCID), a group of rare, genetic conditions, are at risk for life-threatening illnesses unless diagnosed and treated early. Even after early identification through newborn screening, parents of children with SCID embark on a complex journey marked by a variety of informational and emotional support needs. This paper explored the types of uncertainties experienced by parents of a child with SCID diagnosed through newborn screening. We conducted semi-structured interviews with 26 parents to discuss the types of uncertainty experienced, including scientific, practical, personal, and existential. Each interview was recorded, transcribed, and coded. Using deductive and inductive content analysis, we describe the type of uncertainty experienced across each stage of the SCID journey. We found that uncertainties in the SCID journey were chronic and multifaceted. Some uncertainties were more prominent at certain points of the journey whereas others spanned multiple stages. Parents expressed a variety of negative emotional reactions to uncertainty, from anxiety, worry, and fear, to doubt, guilt, or grief, and even anger, frustration, and depression. The results speak to the need for healthcare providers to prepare parents for the SCID journey by providing resources to help manage and cope with uncertainty.