Two surfactant protein A (SP-A) genes and several alleles for each SP-A locus have been previously described. In this report we investigate the potential usefulness of the SP-A loci as markers for genetic studies. We establish conditions that allow the identification of alleles with very similar sequences; We also determine the degree of polymorphism for each SP-A locus: The heterozygosity and polymorphism information content (PIC) values for the SP-A1 locus are 0.63 and 0.55, respectively, and for the SP-A2 locus are 0.50 and 0.56. In the course of these studies, we identify one new SP-A2 allele and show that the SP-A1 and SP-A2 loci are in linkage disequilibrium (P < 0.000001). We also identify 19 of the 20 possible haplotypes in a population of n = 239. Nine of the observed haplotypes reach statistical significance (P < 0.01) in this population, and the segregation of two haplotypes (6A2/1A0 and 6A4/1A) without recombination is verified in a family pedigree. These data together indicate that both SP-A loci are sufficiently polymorphic to be good markers for use in genetic studies. Furthermore, the finding of one novel allele suggests that additional unknown SP-A alleles are yet to be found.

The expression of many genes for which products are involved in inflammation is controlled by the transcriptional regulator nuclear factor (NF)-kappa B. Because surfactant protein (SP) A is involved in local host defense in the lung and alters immune cell function by modulating the expression of proinflammatory cytokines as well as surface proteins involved in inflammation, we hypothesized that SP-A exerts its action, at least in part, via activation of NF-kappa B. We used gel shift assays to determine whether SP-A activated NF-kappa B in the THP-1 cell line, a human monocytic cell line. Activation of NF-kappa B in THP-1 cells by SP-A doses as low as 1 microgram/ml occurred within 30 min of SP-A treatment, peaked at 60 min, and then declined. This activation is inhibited by known inhibitors of NF-kappa B or by simultaneous treatment of the cells with surfactant lipids. Moreover, the NF-kappa B inhibitors blocked SP-A-dependent increases in tumor necrosis factor-alpha mRNA levels. These observations suggest a mechanism by which SP-A plays a role in the pathogenesis of some lung conditions and point to potential therapeutic measures that could be used to prevent SP-A induced inflammation in the lung.

Polycystic kidney disease (ADPKD) is a condition with an autosomal dominant mode of inheritance and adult onset. Two forms of the disease, ADPKD1 and ADPKD2, caused by mutations in PKD1 and PKD2, respectively, are very similar, except that ADPKD1 patients run a more severe course. At the cellular level, ADPKD1 was first shown to be recessive, since somatic second hits are perhaps necessary for cyst formation. The near identical phenotype had suggested that ADPKD1 and ADPKD2 might have a similar pathogenesis and that the two gene products, poly- cystins 1 and 2, are part of a common developmental pathway. Work in transgenic mice showed that somatic loss of Pkd2 expression is necessary for renal cyst formation, and recently we showed that somatic mutations inactivating the inherited healthy allele were present in 9 of 23 cysts from a human ADPKD2 kidney, supporting a two-hit loss-of-function model for ADPKD2 cystogenesis. Here, we provide the first direct genetic evidence that polycystins 1 and 2 do interact, perhaps as part of a larger complex. In cystic DNA from a kidney of an ADPKD1 patient, we showed somatic mutations not only in the PKD1 gene of certain cysts, but also in the PKD2 gene of others, generating a trans -heterozygous state with mutations in both genes. One mutation in PKD1 is of germinal nature and the mutation in the PKD2 gene is of somatic nature. The implications of such a situation are enormous, not only for ADPKD, but also for many other conditions with phenotypic heterogeneity and age-dependent penetrance.

Familial Mediterranean Fever (FMF) is an autosomal recessive disease of high prevalence within Mediterranean countries and particularly common in four ethnic populations: Arabs, non-Ashkenazi Jews, Armenians, and Turks. The responsible gene MEFV has been assigned to chromosome 16p13.3. Our aim was to establish the frequencies of the most common mutations in Greek-Cypriots. We found that 1 in 25 is a carrier of one of three mutations. V726A, M694V, and F479L. In 68 Grek-Cypriot FMF chromosomes analyzed, we found V726A (25%), F479L (20.6%), M694V (17.6%), and others (36.8%). Mutation F479L, relatively common in this population, is very rare elsewhere. Our study indicates that FMF is not a rare condition in Cyprus and that, because of the significant morbidity associated with this disorder, which is often diagnosed only after unnecessary surgeries, a newborn screening program to detect affected in this population may be warranted.