Cystic fibrosis (CF) is the most common inherited life-limiting disorder among Caucasians. The implementation of CF newborn screening has enabled early diagnosis and prompt treatment onset. However, several factors may affect circulating levels of immunoreactive trypsinogen leading to a normal CF newborn screen. This case aims to highlight the importance of taking clinical manifestations as a strong factor for the diagnosis of CF even in the presence of a negative newborn screen. This may allow early referral to a specialized CF center where the onset of appropriate treatment can be implemented, thereby positively impacting the course of the disease.

Background: Hereditary hemorrhagic telangiectasia (HHT) formerly known as Osler-Weber-Rendu syndrome is a rare autosomal dominant disorder characterized by vascular dysplasia and a wide spectrum of clinical manifestations. Case presentation: We report the case of an undiagnosed pediatric patient who presented hypoxemia on clinical exam as the only suggestive feature for the presence of HHT. Conclusions: Although HHT diagnosis is based on the finding of characteristic clinical features genetic testing should also be implemented when a family history of the disease is present to help confirm or refute the diagnosis.