Exhaled nitric oxide (NO) may aid in monitoring pulmonary disease. The single-breath NO profile (subjects with nose clip) was described as a NO peak followed by a plateau (NO(PLAT)). Published exhaled NO values vary greatly, possibly due to contamination with nasal NO and differing respiratory maneuvers. We developed a technique to measure pulmonary NO, without nasal NO, by having the subject maintain a positive expiratory pressure (ensuring vellum closure), and we examined the variation in NO(PLAT) over a range of expiratory flows (4.2 to 1,550 ml/s). NO(PLAT) values rose almost 35-fold (3.2 +/- 1.4 ppb to 110.5 +/- 54.8 ppb) with decreasing flow, described by NO(PLAT) = 208.6795 x (flow rate)(-0.5995). However, NO excretion showed an almost 11-fold rise as flow increased. In summary, we present a simple technique for measuring exhaled NO without contamination by nasal NO. There is a marked flow dependence of exhaled NO concentration and excretion. Exhaled pulmonary NO is best measured at very low flow rates to amplify the signal and must be related to the expiratory flow employed.

BACKGROUND & AIMS:Patients with severe bile salt export pump (BSEP) deficiency present as infants with progressive cholestatic liver disease. We characterized mutations of ABCB11 (encoding BSEP) in such patients and correlated genotypes with residual protein detection and risk of malignancy. METHODS: Patients with intrahepatic cholestasis suggestive of BSEP deficiency were investigated by single-strand conformation polymorphism analysis and sequencing of ABCB11. Genotypes sorted by likely phenotypic severity were correlated with data on BSEP immunohistochemistry and clinical outcome. RESULTS: Eighty-two different mutations (52 novel) were identified in 109 families (9 nonsense mutations, 10 small insertions and deletions, 15 splice-site changes, 3 whole-gene deletions, 45 missense changes). In 7 families, only a single heterozygous mutation was identified despite complete sequence analysis. Thirty-two percent of mutations occurred in >1 family, with E297G and/or D482G present in 58% of European families (52/89). On immunohistochemical analysis (88 patients), 93% had abnormal or absent BSEP staining. Expression varied most for E297G and D482G, with some BSEP detected in 45% of patients (19/42) with these mutations. Hepatocellular carcinoma or cholangiocarcinoma developed in 15% of patients (19/128). Two protein-truncating mutations conferred particular risk; 38% (8/21) of such patients developed malignancy versus 10% (11/107) with potentially less severe genotypes (relative risk, 3.7 [confidence limits, 1.7-8.1; P = .003]). CONCLUSIONS: With this study, >100 ABCB11 mutations are now identified. Immunohistochemically detectable BSEP is typically absent, or much reduced, in severe disease. BSEP deficiency confers risk of hepatobiliary malignancy. Close surveillance of BSEP-deficient patients retaining their native liver, particularly those carrying 2 null mutations, is essential. Abbreviations:ABC, ATP-binding cassette; AFP, α-fetoprotein; BSEP, bile salt export pump; CpG, cytosine-guanine; CC, cholangiocarcinoma; FIC1, familial intrahepatic cholestasis 1; γ-GT, γ-glutamyl transferase; HCC, hepatocellular carcinoma; IC, intracellular loop; MDR1, multidrug resistance protein 1; MDR3, multidrug resistance protein 3; MRP2, multidrug resistance-associated protein 2; NBF, nucleotide-binding fold; OLT, orthotopic liver transplantation; PEBD, partial external biliary diversion; PFIC, progressive familial intrahepatic cholestasis; PCR, polymerase chain reaction; RE, restriction endonuclease; SSCP, single-strand conformation polymorphism; TM, transmembrane domain; UDCA, ursodeoxycholic acid Acknowledgements We thank the families and the Children's Liver Disease Foundation for support and encouragement, and those who referred families for analysis, including Drs U Baumann, W Berquist, M de Vree, K Emerick, G Ferry, M Finegold, W Hardikar, S Horslen, R Houwen, R Jaffe, L Klomp, F Lacaille, K Mann, P McKiernan, H Sharp, R Sokol, E Sturm, L Szönyi, J Taminou, and J Watkins. We also thank Dr R Garcia-Kennedy for access...

We identified 15 kindreds including 29 individuals affected with ARC syndrome. First, we excluded linkage to the candidate genes ATP8B1 and ABCB11 (ref. 10), which are implicated in other disorders that cause neonatal cholestasis with low gGT activity. We then carried out a genome-wide linkage scan using the Affymetrix 10K SNP chip [11][12][13][14] in seven affected individuals from six consanguineous kindreds with ARC. This scan identified eight regions of extended homozygosity shared by all affected individuals. We analyzed these regions further by typing microsatellite markers in 64 individuals from 14 consanguineous families ( Fig. 1 and Supplementary Fig.

No abstract

The elucidation of genetic causes of cholestasis has proved to be important in understanding the physiology and pathophysiology of the liver. Protein-truncating mutations in the tight junction protein 2 gene (TJP2) are shown to cause failure of protein localisation, with disruption of tight-junction structure leading to severe cholestatic liver disease. This contrasts with the embryonic-lethal knockout mouse, highlighting differences in redundancy in junctional complexes between organs and species.

No abstract

Background & Aims-Progressive familial intrahepatic cholestasis (PFIC) with normal serum levels of gamma-glutamyltranspeptidase can result from mutations in ATP8B1 (encoding familial intrahepatic cholestasis 1 [FIC1]) or ABCB11 (encoding bile salt export pump [BSEP]). We evaluated clinical and laboratory features of disease in patients diagnosed with PFIC, who carried mutations in ATP8B1 (FIC1 deficiency) or ABCB11 (BSEP deficiency). Our goal was to identify features that distinguish presentation and course of these 2 disorders, thus facilitating diagnosis and elucidating the differing consequences of ATP8B1 and ABCB11 mutations.

No abstract