This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Primary Aim: To identify CFTR mutations in patients with PSC using exhaustive CFTR genotyping and to compare these results with control patients. In collaboration with the group in Toronto, we will utilize multiplex heteroduplex gel shift analysis with directed sequencing. All mutations, variants, and polymorphisms will be identified.Secondary Aim: To perform a functional assessment of CFTR chloride function in vivo ivivo in patients with PSCAdult-onset disease presenting with single organ involvement (e.g. chronic pancreatitis, male infertility, adult PSC) are associated with variants/polymorphisms in CFTR rather than homozygous disease proven mutations. Since many changes in the CFTR gene are not disease proven and referred to as variants, it is critical to assess phenotype (chloride channel function) and correlate that with genotype. There are many CFTR variants and polymorphisms which do not cause classical cystic fibrosis. The issue is whether these mild mutations have a functional consequence.Nasal Potential Difference Testing (NTPD) allows direct analysis of CFTR function in subjects. This highly sensitive test will be critical in testing the overall hypothesis of this study. This will be performed in the NTPD laboratory within the GCRC at BIDMC.We will identify CFTR variants, which are alterations in the CFTR gene but are not proven to be disease causing (e.g. M470V). This is the rationale for why it is critical to assess CFTR function by NTPD. We have worked closely and published multiple studies using NTPD. In addition, we are one of the few sites approved by the CF Foundation and Therapeutics Development Network (TDN) for NTPD analyses.All aspects of NTPD will be analyzed and correlated with genotype. This includes responses to amiloride, chloride-free solution, isoproterenol with chloride free solution, and ATP. The NTPD results will also be correlated with that of the sweat tests. Sweat test results are abnormal if there are severe CFTR mutations that r
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