ABCMdb

PMID: 10649505

Yee K, Robinson C, Hurlock G, Moss RB, Wine JJ
Novel Cystic Fibrosis mutation L1093P: functional analysis and possible Native American origin.
Hum Mutat. 2000 Feb;15(2):208., [PubMed]

Sentences

No. Mutations Sentence Comment

5 ABCC7 p.Leu1093Pro Functional analysis using forskolin-stimulated efflux of 125 I in HEK cells transfected with an ABCC7 construct harboring the L1093P mutation confirmed that cAMP-mediated anion efflux was abnormal, but some function was preserved. Login to comment 6 ABCC7 p.Asn1303Lys ABCC7 p.Leu1093Pro Analysis of parental DNA established that N1303K was of English origin, while L1093P was of Greek, Irish or Native American (Cherokee) origin. Login to comment 7 ABCC7 p.Leu1093Pro Given the intensive screening for CF mutations in European populations, we hypothesize that L1093P is of Native American origin. Login to comment 11 ABCC7 p.Asn1303Lys We provide evidence that cells transfected with ABCC7 harboring this mutation are severely deficient in their ability to increase anion conductance in response to forskolin. The subject is pancreatic insufficient (the other mutation is N1303K, known to be a severe mutation) and had lung disease severe enough to require a lung transplant. Login to comment 12 ABCC7 p.Leu1093Pro Preliminary evidence indicates that the L1093P mutation might be of Native American origin. Login to comment 13 ABCC7 p.Asn1303Lys METHODS Following a conventional genotyping in 1992 that revealed N1303K/unknown, the subject was referred for more extensive genetic analysis. Login to comment 42 ABCC7 p.Asn1303Lys Exon 21 was heterozygous for C/G at position 4041, confirming the previously detected N1303K mutation in this subject. Login to comment 47 ABCC7 p.Leu1093Pro The subject is heterozygous for T/C at position 3410, resulting in L1093P. Login to comment 51 ABCC7 p.Asn1303Lys ABCC7 p.Leu1093Pro The father was heterozygous for N1303K, and the mother for L1093P (Fig. 1a). Login to comment 52 ABCC7 p.Asn1303Lys ABCC7 p.Leu1093Pro The N1303K mutation was paternal, and the L1093P mutation was maternal. Login to comment 65 ABCC7 p.Leu1093Pro ABCC7 p.Leu1093Pro Exon 17b 1 2 3 4 5 B. C. -6 -4 -2 0 2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 Wild-Type L1093P (T3410C) Vector Only EFFLUXRATE 30s EFFLUX INTERVALS (n) Physiological assay of the L1093P missense mutation. Login to comment 66 ABCC7 p.Leu1093Pro ABCC7 p.Leu1093Pro To assess the anion channel function of CFTR harboring the L1093P mutation, HEK cells transiently expressing either plasmid alone, WT- ABCC7, or L1093P- ABCC7 were assayed for 125 I efflux in the absence and presence of forskolin. The extent to which the rate of efflux increases following forskolin is correlated with the number of active CFTR channels in the membrane (n), their open probability (Po), and their conductance (γ). Login to comment 67 ABCC7 p.Leu1093Pro As shown in Fig. 1c, efflux from the L1093P mutation was significantly reduced relative to WT ABCC7, but was slightly but significantly elevated relative to vector alone. Login to comment 68 ABCC7 p.Gly551Asp In this same assay, mutations such as ∆F508-ABCC7 and G551D were indistinguishable from vector alone (data not shown). Login to comment 70 ABCC7 p.Asn1303Lys ABCC7 p.Leu1093Pro The present mutation, L1093P, was found in association with N1303K in a pancreatic insufficient subject who had lung disease severe enough to require a transplant. Login to comment 71 ABCC7 p.Asn1303Lys N1303K has been identified as a severe mutation (Chastre et al. 1991; Osborne et al. 1992). Login to comment 72 ABCC7 p.Gly551Asp ABCC7 p.Leu1093Pro The clinical phenotype and our physiological data indicate that L1093P should also be considered a severe mutation, yet it does retain some function, in contrast with mutations such as ∆F508-ABCC7 and G551D-ABCC7 that are indistinguishable from vector controls in this assay. Login to comment 73 ABCC7 p.Leu1093Pro Dysfunction of L1093P. Login to comment 74 ABCC7 p.Leu1093Pro The basis of the dysfunction of L1093P was not determined. Login to comment 75 ABCC7 p.Leu1093Pro L1093P occurs in the part of exon 17b, residues 1035-1102, that forms the 4th intracellular loop of ABCC7(Cotton et al. 1996; Seibert et al. 1996). Login to comment 78 ABCC7 p.Ala1067Thr ABCC7 p.Gln1071Pro Other mutations in this region e.g. A1067T (Cotton et al. 1996; Seibert et al. 1996) and Q1071P (Seibert et al. 1996) are associated with pancreatic insufficiency, yet retain partial function when tested with efflux assays. Login to comment 81 ABCC7 p.Leu1093Pro Possible Native American Origin of L1093P. Login to comment 83 ABCC7 p.Asn1303Lys The N1303K mutation was paternal. Login to comment 84 ABCC7 p.Asn1303Lys Although N1303K is more prevalent in Southern Europe, it accounts for ~0.5% of CF mutations in England (Schwarz et al. 1995). Login to comment 85 ABCC7 p.Leu1093Pro The L1093P mutation was maternal. Login to comment 86 ABCC7 p.Leu1093Pro Previous comprehensive screenings of European populations have not detected the L1093P mutation. Login to comment 88 ABCC7 p.Leu1093Pro Because of the high sensitivity of DGGE, which is essentially 100% when optimized (Gejman et al. 1998), these figures indicate that the L1093P mutation, if present in these populations, probably accounts for < 0.2% of CF mutations. Login to comment 89 ABCC7 p.Leu1093Pro Therefore, we consider the alternative hypothesis that L1093P might be of Native American origin. Login to comment 91 ABCC7 p.Arg1162* Zuni have a CF incidence of 1/333 caused entirely by a single mutation, R1162X (Kessler et al. 1996), which a previous study of Pueblo CF subjects indicated was of European origin (Mercier et al. 1994). Login to comment 92 ABCC7 p.Asp648Val However, haplotype analysis in that same study showed that 3849+10kb C→T(Highsmith et al. 1994) (n = 3), was associated with different haplotypes than those linked to the same mutation in Caucasians, and a novel mutation, D648V (n = 1) is so far unique to the Pueblo population (Mercier et al. 1994). Login to comment