Mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene typically cause severe health complications in multiple organ systems, including the respiratory and gastrointestinal systems. Certain CFTR mutations, however, cause milder clinical phenotypes which may delay confirmatory diagnosis and treatment. Moreover, rare CFTR variants are not studied frequently or approved for genotype specific CFTR modulator therapies, creating further disadvantage. Herein, we describe a personalized medicine approach for a CF patient with three CFTR variants and mild clinical disease to aid in the diagnosis of CF and development of an optimized treatment plan. This strategy relied on the synergistic combination of advanced genetic analyses, patient-derived models of CFTR function and modulation, and personalized clinical care delivery. Whole Exome Sequencing revealed three compound heterozygous CFTR variants: c.2249C>T (p.P750L), c.1408G>A (p.V470M), and c.1251C>A (p.N417K). The CFTR channel function and nature of protein defects for both V470M and N417K mutations are not previously characterized. Patient-derived intestinal organoid models demonstrated residual CFTR channel activity, with improvement in channel function following treatment with the CFTR modulators. / n vitro studies in heterologous model system demonstrated that P750L has the features of Class II CFTR mutations, whereas V470M/N417K exhibited characteristics of Class II, III, and IV mutations, with all three variants responding to the combination modulator therapy of elexacaftor, tezacaftor, and ivacaftor (ETI) and showing functional rescue to near-wild-type CFTR levels. The laboratory data was then utilized to inform patient care, including off-label prescription of ETI. Following 18 months of ETI therapy, significant improvements were noted in key clinical outcomes, including sweat chloride, nutritional parameters, and respiratory and gastrointestinal symptoms. This study demonstrates a personalized medicine approach across clinical and laboratory domains used to care for CF patients with atypical symptoms and/or rare CFTR mutations.

Myelofibrosis (MF) in the pediatric setting is uncommon and appears to be pathogenically heterogeneous. MF due to intrinsic bone marrow abnormality (IMF) is distinct from adult-type Primary myelofibrosis (PMF) as they can lack the common genetic markers of clonality. To date, all but two reported patients with pediatric MF and mutated MPIG6B have been Arabic, and all reported cases have had a family history of consanguinity. Here we report the first North American patient of European ancestry with pediatric MF in whom novel compound heterozygous mutations of MPIG6B were identified.