MET exon 14 skipping mutations in non-small-cell lung cancer: real-world data from the Italian biomarker ATLAS database.

BACKGROUND: Mesenchymal-epithelial transition (MET) exon 14 (METex14) skipping mutation is a rare alteration in non-small-cell lung cancer (NSCLC), occurring in about 3%-4% of cases. Here we report disease and patient characteristics, and efficacy and tolerability of MET inhibitors among advanced METex14 NSCLC patients from the Italian real-world registry ATLAS. MATERIALS AND METHODS: Clinical-pathological and molecular data, and treatment efficacy/tolerability outcomes were retrospectively collected from the ATLAS registry. RESULTS: From July 2020 to July 2023 a total of 146 METex14 advanced NSCLC patients were included across 27 Italian centers. Median age was 74 years, and most patients were male (52%), with an Eastern Cooperative Oncology Group performance status < 2 (72%) and adenocarcinoma subtype (83%). One hundred and twenty-five out of 146 (86%) patients received at least one line of systemic anticancer therapy. Fifty-six (38%) were treated with capmatinib and 34 (23%) with tepotinib. 29% and 52% of them received targeted treatment in the first and second line, respectively. In the cohort of patients treated with MET inhibitors, the response rate (RR) was 37% (33% in previously treated patients and 46% in treatment-naïve) with a disease control rate of 62%. With a median follow-up of 10.8 months, progression-free survival was 6.6 months [95% confidence interval (CI) 4.3-8.3 months] and overall survival was 10.7 months (95% CI 7.2-19.3 months). In patients with measurable brain metastases (17 cases), the intracranial RR was 41%. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 12% of patients with grade 3 peripheral edema in 7% of cases. A fatal adverse reaction occurred in one patient due to pneumonitis. TRAEs-related dose reduction and discontinuation were reported in 6% and 8% of cases, respectively. CONCLUSION: Capmatinib and tepotinib represent an effective treatment option in NSCLC patients with METex14. Real-world efficacy outcomes are worse than those reported in prospective clinical trials. Their activity is more pronounced in the treatment-naïve population, suggesting that this is the right setting in the management of patients with METex14.

Bone metastases are associated with worse prognosis in patients affected by metastatic colorectal cancer treated with doublet or triplet chemotherapy plus bevacizumab: a subanalysis of the TRIBE and TRIBE2 trials.

BACKGROUND: Colorectal cancer (CRC) is one of the most common cancers; ∼20% of patients have metastases at diagnosis, and 50%-60% subsequently develop metachronous metastases. Bone involvement, despite being rare, is usually associated with higher disease burden, worse prognosis, impaired quality of life, and significant health-related cost. In the last few years, following the positive results of the TRIBE and TRIBE2 trials, the association of FOLFOXIRI plus bevacizumab has become the new standard of care for metastatic CRC. Despite being highly efficacious in all subgroups, little is known about the activity of this regimen in patients with bone metastases. PATIENTS AND METHODS: We carried out a pooled analysis of TRIBE and TRIBE2 studies focusing on patients with skeletal deposits. RESULTS: Our analyses on the whole population showed that patients with baseline bone involvement reported shorter overall survival [OS; 14.0 versus 26.2 months; hazard ratio (HR) 2.04, 95% confidence interval (CI) 1.46-2.87; P < 0.001] and progression-free survival (PFS; 6.2 versus 11.1 months; HR 1.96, 95% CI 1.42-2.69; P < 0.001) compared with those without bone metastases; no significant interaction with the treatment was reported for PFS (P = 0.094) and OS (P = 0.38). Bone metastases had a negative prognostic implication in the multivariate analysis (HR 2.24, 95% CI 1.54-3.26; P < 0.001). Furthermore, patients with bone lesions at first radiological progression (including those with baseline bone metastases) had a shorter OS compared with those who progressed in other sites (10.4 versus 13.2 months; HR 1.48, 95% CI 1.15-1.91; P = 0.002). A trend toward inferior OS (7.5 versus 11 months, HR 1.50, 95% CI 0.92-2.45; P = 0.10) appeared in patients with basal skeletal deposits compared with those with bone involvement at first radiological progression. CONCLUSIONS: Our study confirmed the negative prognostic impact of bone metastases in CRC. Furthermore, we demonstrated for the first time that the survival advantage of triplet chemotherapy plus bevacizumab is maintained even in this prognostically unfavorable subgroup.

Evaluation of COVID-19 impact on DELAYing diagnostic-therapeutic pathways of lung cancer patients in Italy (COVID-DELAY study): fewer cases and higher stages from a real-world scenario.

INTRODUCTION: COVID-19 has disrupted the global health care system since March 2020. Lung cancer (LC) patients (pts) represent a vulnerable population highly affected by the pandemic. This multicenter Italian study aimed to evaluate whether the COVID-19 outbreak had an impact on access to cancer diagnosis and treatment of LC pts compared with pre-pandemic time. METHODS: Consecutive newly diagnosed LC pts referred to 25 Italian Oncology Departments between March and December 2020 were included. Access rate and temporal intervals between date of symptoms onset and diagnostic and therapeutic services were compared with the same period in 2019. Differences between the 2 years were analyzed using the chi-square test for categorical variables and the Mann-Whitney U test for continuous variables. RESULTS: A slight reduction (-6.9%) in newly diagnosed LC cases was observed in 2020 compared with 2019 (1523 versus 1637, P = 0.09). Newly diagnosed LC pts in 2020 were more likely to be diagnosed with stage IV disease (P < 0.01) and to be current smokers (someone who has smoked more than 100 cigarettes, including hand-rolled cigarettes, cigars, cigarillos, in their lifetime and has smoked in the last 28 days) (P < 0.01). The drop in terms of new diagnoses was greater in the lockdown period (percentage drop -12% versus -3.2%) compared with the other months included. More LC pts were referred to a low/medium volume hospital in 2020 compared with 2019 (P = 0.01). No differences emerged in terms of interval between symptoms onset and radiological diagnosis (P = 0.94), symptoms onset and cytohistological diagnosis (P = 0.92), symptoms onset and treatment start (P = 0.40), and treatment start and first radiological revaluation (P = 0.36). CONCLUSIONS: Our study pointed out a reduction of new diagnoses with a shift towards higher stage at diagnosis for LC pts in 2020. Despite this, the measures adopted by Italian Oncology Departments ensured the maintenance of the diagnostic-therapeutic pathways of LC pts.

The lung immuno-oncology prognostic score (LIPS-3): a prognostic classification of patients receiving first-line pembrolizumab for PD-L1 ≥ 50% advanced non-small-cell lung cancer.

BACKGROUND: To stratify the prognosis of patients with programmed cell death-ligand 1 (PD-L1) ≥ 50% advanced non-small-cell lung cancer (aNSCLC) treated with first-line immunotherapy. METHODS: Baseline clinical prognostic factors, the neutrophil-to-lymphocyte ratio (NLR), PD-L1 tumour cell expression level, lactate dehydrogenase (LDH) and their combination were investigated by a retrospective analysis of 784 patients divided between statistically powered training (n = 201) and validation (n = 583) cohorts. Cut-offs were explored by receiver operating characteristic (ROC) curves and a risk model built with validated independent factors by multivariate analysis. RESULTS: NLR < 4 was a significant prognostic factor in both cohorts (P < 0.001). It represented 53% of patients in the validation cohort, with 1-year overall survival (OS) of 76.6% versus 44.8% with NLR > 4, in the validation series. The addition of PD-L1 ≥ 80% (21% of patients) or LDH < 252 U/l (25%) to NLR < 4 did not result in better 1-year OS (of 72.6% and 74.1%, respectively, in the validation cohort). Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 2 [P < 0.001, hazard ratio (HR) 2.04], pretreatment steroids (P < 0.001, HR 1.67) and NLR < 4 (P < 0.001, HR 2.29) resulted in independent prognostic factors. A risk model with these three factors, namely, the lung immuno-oncology prognostic score (LIPS)-3, accurately stratified three OS risk-validated categories of patients: favourable (0 risk factors, 40%, 1-year OS of 78.2% in the whole series), intermediate (1 or 2 risk factors, 54%, 1-year OS 53.8%) and poor (>2 risk factors, 5%, 1-year OS 10.7%) prognosis. CONCLUSIONS: We advocate the use of LIPS-3 as an easy-to-assess and inexpensive adjuvant prognostic tool for patients with PD-L1 ≥ 50% aNSCLC.

Osimertinib beyond disease progression in T790M EGFR-positive NSCLC patients: a multicenter study of clinicians' attitudes.

BACKGROUND: In most cases, T790M EGFR-positive NSCLC patients receiving osimertinib developed "non-drugable" progression, as the patients with common EGFR-sensitizing mutations were treated with first-line osimertinib. In both settings, chemotherapy represents the standard treatment and local ablative treatments (LATs) are potential useful options in the case of oligo-progression. METHODS: We conducted a study on "post-progression" (pp) outcomes of T790M EGFR-positive NSCLC patients treated with osimertinib, according to the therapeutic strategy applied: osimertinib beyond progression (± LATs), "switched therapies" or best supportive care only (BSC). RESULTS: 144 consecutive patients were evaluated: 53 (36.8%) did not received post-progression treatments (BSC), while 91 (63.2%) patients received at least 1 subsequent treatment; 50 patients (54.9%) received osimertinib beyond disease progression [19 (20.9%) of them with adjunctive LATs] and 41 (45.1%) a switched therapy. Median ppPFS (progression-free survival) and median ppOS (overall survival) of patients who received osimertinib beyond progression vs. switched therapies were 6.4 months vs. 4.7 months, respectively [HR 0.57 (95% CI 0.35-0.92), p = 0.0239] and 11.3 months vs 7.8 months, respectively [HR 0.57 (95% CI 0.33-0.98), p = 0.0446]. Among patients who received osimertinib beyond progression with and without LATs median ppPFS was 6.4 months and 5.7 months, respectively [HR 0.90 (95% CI 0.68-1.18), p = 0.4560], while median ppOS was 20.2 months and 9.9 months, respectively [HR 0.73 (95% CI 0.52-1.03), p = 0.0748]. At the univariate analysis, the only factor significantly related to the ppPFS was the therapeutic strategy in favor of osimertinib beyond progression (± LATs). Moreover, the only variable which was significantly related to ppOS at the multivariate analysis was osimertinib beyond progression (± LATs). CONCLUSION: Our study confirmed that in clinical practice, in case of "non-druggable" disease progression, maintaining osimertinib beyond progression (with adjunctive LATs) is an effective option.

The 5' sequence of human factor XII gene contains transcription regulatory elements typical of liver specific, estrogen-modulated genes.

The human Factor XII gene codes for a serine proteinase synthesized in liver that activates both the coagulation and the fibrinolytic cascades. The nucleotide sequence analysis of a HincII-HincII 3129 bp fragment was performed showing that the FXII promoter region contains neither CAAT and TATA regulatory elements, nor GC islands, but revealing the presence of two tandemly repeated sequences in opposite orientation, two LF-A1 elements typical of the liver specific genes and one estrogen responsive element, that substantiates the observation of Factor XII gene modulation by estrogens.

Molecular basis of estrogen regulation of Hageman factor XII gene expression.

Estrogen therapy has been reported to cause multiple alterations in hemostasis and to increase blood levels of several procoagulants, including Hageman factor [factor XII (FXII)]. Liver FXII gene expression has been investigated in ovariectomized rats, treated or not with 17 beta-estradiol. A 6-fold stimulation of FXII gene transcription was observed in treated compared to untreated animals, indicating that 17 beta-estradiol is able to induce FXII gene expression in vivo. We have recently shown that human FXII promoter contains an imperfect palindrome, 5'-GGGCAnnnTGACC-3', at position -43/-31 resembling the consensus estrogen-responsive element (ERE). Portions of different length of the FXII promoter were fused to the chloramphenicol acetyltransferase (CAT) coding sequence and transiently cotransfected with human estrogen receptor (ER) into NIH3T3 and HepG2 cells in the presence or absence of 17 beta-estradiol. A 230-base pair fragment of FXII promoter, spanning nucleotides - 181/49, conferred a strong estrogen responsiveness to the CAT reporter gene, suggesting that a functional ERE resides in this region. Cognate receptors, such as those for thyroid hormone or retinoic acid, did not stimulate CAT activity. Gel mobility assays demonstrated a specific interaction between ER and the 230-bp FXII promoter fragment containing the putative ERE palindrome. Similar results were obtained when an oligonucleotide spanning the consensus ERE was used; the complex between ER and FXII promoter sequences was supershifted after the addition of an anti-ER monoclonal antibody. Insertion of FXII-ERE into the heterologous thymidine kinase promoter conferred a strong estrogen responsiveness that was abolished by mutations of the 5'-half of the palindrome. These results represent the first demonstration at the molecular level of the regulation of a blood coagulation factor gene by 17 beta-estradiol as well as the first identification of a functional ERE within this class of genes.

Identification of a putative binding site for negatively charged surfaces in the fibronectin type II domain of human factor XII--an immunochemical and homology modeling approach.

Monoclonal antibodies directed against functional sites of proteins provide useful tools for structure-function studies. Here we describe a mAb, KOK5, directed against the heavy chain region of human coagulation factor XII (FXII), which inhibits kaolin-induced clotting activity by preventing the binding of FXII to kaolin. Furthermore, mAb KOK5 enhances FXII susceptibility for cleavage by kallikrein and supports FXII autoactivation. Hence, mAb KOK5 likely is directed against the binding site of FXII for negatively charged surfaces. Screening of two phage-displayed random peptide libraries with mAb KOK5 selected phages that could be grouped on the basis of two amino acid consensus sequences: A) FXFQTPXW and B) HQ/LCTHR/KKC. Sequence A contains two motifs: one shares homology with FXII amino acid residues 30-33 (FPFQ), the second one with residues 57-60 (TPNF); both amino acid stretches belonging to the fibronectin type II domain of FXII. Sequence B also reveals homology with part of the fibronectin type II domain, i.e. the stretch 40-47 (HKCTHKGR). A three-dimensional model of FXII residues 28-65, obtained by homology modeling, indicated that the three amino acid stretches 30-33, 40-47 and 57-60 are close to each other and accessible for the solvent, i.e. in a form available for interaction with the monoclonal antibody, suggesting that mAb KOK5 recognizes a discontinuous epitope on the fibronectin type III domain of FXII. Peptides corresponding to FXII sequences 29-37 (FXII29-37) or 39-47 (FXII39-47), were synthesized and tested for the capability to inhibit FXII binding to negatively charged surfaces. Peptide FXII39-47 inhibited the binding of labeled FXII to kaolin and effectively prevented both dextran sulfate- and kaolin-induced activation of the contact system in plasma. Hence, we suggest that the fibronectin type II domain of FXII, in particular residues 39 to 47, contribute to the binding site of FXII for negatively charged surfaces.

Androgen receptor in the thumb pad of Rana esculenta: dynamic aspects.

The androgen receptor (dissociation constant, 6 x 10(-9) mol/l) present in the 105 000 g cytosol fraction of the thumb pad of Rana esculenta is hormone dependent. The number of testosterone binding sites decreased in the absence of the testes and in long-term castrated animals (75 days) became undetectable. Administration of testosterone (50 ng) induced the replenishment of the cytophasmic androgen receptor; its concentration also varied during the annual reproductive cycle.

Increased glomerular Vwf after kidney irradiation is not due to increased biosynthesis or endothelial cell proliferation.

Kuin, A., Citarella, F., Oussoren, Y. G., Van der Wal, A. F., Dewit, L. G. H. and Stewart, F. A. Increased Glomerular Vwf after Kidney Irradiation is not due to Increased Biosynthesis or Endothelial Cell Proliferation. Radiat. Res. 156, 20-27 (2001). Irradiation of the kidney induces dose-dependent, progressive renal functional impairment, which is partly mediated by vascular damage. It has previously been demonstrated that reduced renal function is preceded by an increased amount of von Willebrand factor (Vwf) in the glomerulus. The underlying mechanism and significance of this observation are unknown but, since it is an important mediator of platelet adhesion, Vwf in increased amounts could be implicated in glomerular thrombosis, resulting in impairment of renal function. Increased Vwf could be the result of increased biosynthesis by endothelial cells, or from increased numbers of endothelial cells after compensatory proliferation induced by irradiation, or it could be secondary to other events. In the present study, expression levels of mRNA for glomerular Vwf and glomerular cell proliferation rates were measured in control mouse kidneys and after irradiation with a single dose of 16 Gy. There were no significant changes in mRNA ratios for Vwf/beta-actin at 10 to 30 weeks after irradiation compared with unirradiated samples, whereas increased amounts of Vwf protein were seen in the glomeruli at these times. Labeling studies with IdU or staining for Ki67 demonstrated that glomerular proliferation was increased from 10 to 30 weeks after irradiation. Despite the increased proliferation rates, there was an absence of glomerular hyperplasia and no increase in the endothelial cell surface coverage in the glomeruli. Staining with antibodies against smooth muscle actin (SMAalpha) revealed that the observed proliferation mainly involved mesangial cells. These results indicate that the increased presence of glomerular Vwf after irradiation is not due to an increased number of endothelial cells per glomerulus, or to an increased production of Vwf. It is presumably secondary to other events, such as increased release of Vwf by damaged endothelial cells or entrapment of Vwf in the irradiated mesangial matrix.

Nutritional intervention in a hemodialysis pregnant woman: a case report.

Pregnancy in dialysis patients is a rare occurrence. When pregnancy does occur, the risk of spontaneous abortion, stillbirth and neonatal complications, such as prematurity and growth retardation, are fairly high. The authors describe their experience in the follow-up of a patient with chronic renal failure who became pregnant during regular dialysis treatment and followed nutritional care. The outcomes were successful and she gave birth to a healthy baby. It is emphasized that special dedication to the nutritional control enabled a good outcome of the pregnancy. The importance of the nutritionist intervention in the follow-up of dialysis patients with the integration of a multidisciplinary staff is stressed.

Estrogen induction and contact phase activation of human factor XII.

This paper reviews data reported in the literature and results of our experiments on the transcriptional control of Factor XII by estrogens and on the activation of Factor XII in the plasma. Coagulation Factor XII (Hageman factor, FXII) is a serine protease secreted by the liver and activated by negative charged surfaces to play roles in fibrinolysis, coagulation, and inflammation. Multiple effects on hemostasis involving these processes via Hageman factor have been reported in relation to estrogen therapy. The nucleotide sequence of 3,174 base pair (bp) DNA at the 5' end of the Factor XII gene indicates that the Factor XII promoter is typical of TATA-less, liver-specific, and serine protease-type eukaryotic genes involved in clotting. In addition the Factor XII promoter contains at position -44/-31 a palindrome similar, but not identical, to an estrogen-responsive element (ERE) together with four hemisite EREs between positions -1314 and -608. These promoter regions may underlie the mechanism by which estrogens enhance Factor XII concentrations in plasma. In vivo, a 6-fold stimulation of FXII gene transcription by 17 beta-estradiol was observed in ovariectomized rats. In vitro a 230-bp promoter fragment of Factor XII (-181/+49) confers a strong 17 beta-estradiol responsiveness onto a chlorampenicol acetyltransferase reporter when transiently co-transfected with the human estrogen receptor. The domain structure of Factor XII allows identification of those parts of the protein with particular functions. cDNA constructs, in which sequences coding for selected domains were deleted, were used to produce recombinant deleted Factor XII proteins in a vacinia virus expression system. To identify the domain(s) responsible for contact phase activation, these recombinant proteins were tested for their capacity to bind to negatively charged substrates, to become activated by kallikrein, and to sustain blood clotting and amidolytic activity. In addition to the N-terminal domain, the growth factor and kringle domains and, to a lesser extent, the polyproline region also interact with negatively charged surfaces and presumably thus contribute to activation.

Molecular studies on DNA sequences coding for factor VII and factor XII of human coagulation.

In this paper are described the immunological and molecular procedures that have allowed the identification and the nucleotide sequence characterization of recombinant cDNA coding for factor XII of human coagulation and have suggested the possible identification of other cDNA clones as coding for factor VII of human coagulation.

Hypothalamic-pituitary-ovarian axis in women with operable breast cancer treated with adjuvant CMF and tamoxifen.

The effect of adjuvant CMF (cyclophosphamide, methotrexate, and 5-fluorouracil) and tamoxifen (TM) on hypothalamic-pituitary-ovarian function was studied in 120 women with stage I-II operable breast cancer. Sixty patients were premenopausal, of whom 25 were treated with CMF for 9 cycles, 25 with CMF for 9 cycles + TM for 2 years, started concurrently, and 10 with TM alone for 2 years. Sixty patients were postmenopausal and they were all treated with TM alone for 2 years. In all groups treatment was started within 4 weeks of mastectomy. Plasma levels of estrone (E1), estradiol-17 beta (E2), follicle-stimulating hormone, luteinizing hormone (LH), prolactin (Prl), testosterone (T) and thyroid-stimulating hormone (TSH) were determined in all patients before surgery and again at 3-month intervals from initiation of the adjuvant therapy. In ten patients of each treatment group FSH-LH and Prl-TSH release was determined following stimulation with releasing hormones. CMF and CMF+TM therapy resulted in amenorrhea in 42/50 premenopausal patients with decrease of E1+E2 (p less than 0.001) and elevation of FSH (p less than 0.001) and LH (p less than 0.01) plasma concentration to postmenopausal levels. In premenopausal women treated with TM a marked increase of E1+E2 (p less than 0.001) was observed with unaltered FSH-LH plasma concentration. A significant fall of Prl also occurred in these patients. In postmenopausal women and premenopausal patients with CMF-induced amenorrhea TM produced a marked fall of FSH-LH and a decrease of Prl plasma level. Plasma TSH and T were not affected in any patient by any of the treatment regimens. The results of the stimulatory tests are in agreement with the hormonal changes observed under basal conditions and indicate that, whereas CMF suppresses the ovary and does not alter hypothalamic-pituitary function, TM induces profound changes of the hypothalamic-pituitary-ovarian axis.

[Hydatidiform mole with coexistent fetus. Cytogenetic features, diagnosis, and management]. / Mola idatiforme con feto coesistente. Aspetti cito-genetici, diagnosi e management.

Hydatidiform mole with coexistent fetus is an unusual entity caused by two distinct types of pregnancy: the first one is a partial hydatidiform mole, while the second is a twin pregnancy in which a mole coexists with a normal fetus. In these two separate genetic entities, the counseling and the mother-fetus prognosis are different. Two cases of mole with coexistent fetus are reported: a partial hydatidiform mole typically tripliod and a partial mole with unusual diploid karyotype. Prenatal diagnosis is remarkable for the evaluation of fetus development related with his karyotype. Triplody excludes all hope of a non-malformed surviving child and termination of pregnancy is desirable, while normal karyotype the possibility of a continuation of pregnancy may be considered.

Nucleotide sequence of a DNA region comprising the gene for elongation factor 1 alpha (EF-1 alpha) from the ultrathermophilic archaeote Pyrococcus woesei: phylogenetic implications.

The gene encoding elongation factor 1 alpha (EF-1 alpha, 1290 bp) of the ultrathermophilic, sulfur-reducing archaeote Pyrococcus woesei was localized within a Bg/II fragment of chromosomal DNA. Sequence analysis showed that the EF-1 alpha gene is the upstream unit of a three-gene cluster comprising the genes for ribosomal protein S10 (306 bp) and transfer RNAser (GGA). The three genes follow each other immediately in the order EF-1 alpha.S10.tRNA(ser) after a putative promoter located 55 bp upstream of the EF-1 alpha gene. Alignment of the derived EF-1 alpha sequence with the corresponding sequences from Eukarya, Bacteria/organelles, and with available archaeal sequences (Sulfolobus, Thermococcus, Methanococcus, Halobacterium) showed that Pyrococcus EF-1 alpha is highly homologous (89% identity) to Thermococcus celer EF-1 alpha, both being strikingly more similar to eukaryotic EF-1 alpha than to bacterial EF-Tu. Unrooted dendrograms computed from aligned sequences by distance matrix and DNA parsimony methods, including evolutionary parsimony, showed the Archaea to be a monophyletic-holophyletic cluster closer to Eukarya than to Bacteria. Both distance matrix and DNA parsimony--although not evolutionary parsimony--support the partition of the known archaeal lineages between the kingdoms Crenarchaeota and Euryarchaeota, and the affiliation of the Pyrococcus-Thermococcus lineage to the Euryarchaeota, of which it is the most primitive offspring. A closer relation of Pyrococcus to Euryarchaeota than to Crenarchaeota was also inferred from sequence analysis of S10 ribosomal proteins.

Assignment of human coagulation factor XII (fXII) to chromosome 5 by cDNA hybridization to DNA from somatic cell hybrids.

Human coagulation factor XII (fXII), a serine protease synthesized in liver and active in plasma, is involved in a wide variety of functions, including blood coagulation, fibrinolysis, bradykinin and complement activation. A complementary DNA (597 bp) encoding amino acid -16 to amino acid 183 of fXII protein was used to determine the chromosomal location of the fXII gene. DNAs from hamster-human somatic cell hybrids were digested with restriction enzymes and hybridized with the fXII cDNA. By the Southern method it was shown that restriction fragments able to hybridize to fXII cDNA are present only in DNA extracted from clones retaining human chromosome 5.