Functional Analysis of the Arg91GIn Substitution in the Factor VIII Binding Domain of von Willebrand Factor Demonstrates Variable Phenotypic Expression

An Arg91Gln substitution in the mature von Willebrand factor (vWF) has been associated with defective binding of vWF to factor VIII (FVIII). We studied four families with members initially classified as having type I von Willebrand disease (vWD) who were either homozygous or heterozygous for the Arg91Gln change. The first family was the original case described by Nishino et al. (1) where three members were homozygous for the Gln91 allele. They had a low FVIII coagulant activity:vWF antigen (VIIIC:vWFAg) ratio, from 0.29 to 0.44, and the ability of their plasma vWF to bind FVIII was markedly decreased. All the heterozygous members had normal vWF and FVIII levels but the capacity of their plasma vWF to bind FVIII was reduced and intermediate between the homozygous members and normals. The affected individual from the second family was heterozygous for the Gln91 allele and demonstrated a VIIIC:vWFAg ratio of 0.98. The FVIII binding assay confirmed the heterozygous status indicating that the moderately low levels of vWF were due to reduced expression of both alleles. The propositus from the third family was also heterozygous and had below normal levels of vWF as well as a low VIIIC:vWFAg ratio of 0.34; however, FVIII binding to her plasma vWF was similar to that of the homozygous individuals suggesting that Gln91-vWF was the major circulating form. Her daughter who has type I vWD inherited the allele without the Gln91 mutation indicating that the expression of this allele was indeed impaired. The heterozygous patient in the fourth family had a vWF level of 24 U/dl but an VIIIC:vWFAg ratio greater than 2. Her plasma vWF showed normal FVIII binding implying that the Gln91 mutation was linked to a defect that repressed the expression of the allele. The Arg91Gln substitution appears to decrease but not eradicate FVIII binding suggesting a critical concentration of vWF be attained before the defect becomes phenotypically important.

Separation of double-wall carbon nanotubes by electronic type and diameter

We introduce a new procedure for the efficient isolation and subsequent separation of double-wall carbon nanotubes (DWCNTs). A simplified, rate zonal ultracentrifugation (RZU) process is first applied to obtain samples of highly-enriched DWCNTs from a raw carbon nanotube material that has both single- and double-wall carbon nanotubes. Using this purified DWCNT suspension, we demonstrate for the first time that DWCNTs can be further processed using aqueous two-phase extraction (ATPE) for sequential separation by electronic structure and diameter. Additionally, we introduce analytical ultracentrifugation (AUC) as a new method for DWCNT characterization to assess DWCNT purity in separated samples. Results from AUC analysis are utilized to compare two DWCNT separation schemes. We find that RZU processing followed by sequential bandgap and diameter sorting via ATPE provides samples of highest DWCNT enrichment, whereas single-step redox sorting of the same raw material through ATPE yields SWCNT/DWCNT mixtures of similar diameter and electronic character. The presented methods offer significant advancement in DWCNT processing and separation while also providing a promising alternative for DWCNT sample analysis.

Enhancing single-wall carbon nanotube properties through controlled endohedral filling

Chemical control of the endohedral volume of single-wall carbon nanotubes (SWCNTs) via liquid-phase filling is established to be a facile strategy to controllably modify properties of SWCNTs in manners significant for processing and proposed applications. Encapsulation of over 20 different compounds with distinct chemical structures, functionalities, and effects is demonstrated in SWCNTs of multiple diameter ranges, with the ability to fill the endohedral volume based on the availability of the core volume and compatibility of the molecule's size with the cross-section of the nanotube's cavity. Through exclusion of ingested water and selection of the endohedral chemical environment, significant improvements to the optical properties of dispersed SWCNTs such as narrowed optical transition linewidths and enhanced fluorescence intensities are observed. Examples of tailoring modified properties towards applications or improved processing by endohedral passivation are discussed.

Simulations to Predict Clinical Trial Outcome of Bevacizumab Plus Chemotherapy vs. Chemotherapy Alone in Patients With First-Line Gastric Cancer and Elevated Plasma VEGF-A

To simulate clinical trials to assess overall survival (OS) benefit of bevacizumab in combination with chemotherapy in selected patients with gastric cancer (GC), a modeling framework linking OS with tumor growth inhibition (TGI) metrics and baseline patient characteristics was developed. Various TGI metrics were estimated using TGI models and data from two phase III studies comparing bevacizumab plus chemotherapy vs. chemotherapy as first‐line therapy in 976 GC patients. Time‐to‐tumor‐growth (TTG) was the best TGI metric to predict OS. TTG, Eastern Cooperative Oncology Group (ECOG) score, albumin level, and Asian ethnicity were significant covariates in the final OS model. The model correctly predicted a decreased hazard ratio favorable to bevacizumab in patients with high baseline plasma VEGF‐A above the median of 113.4 ng/L. Based on trial simulations, in trials enrolling patients with elevated baseline plasma VEGF‐A (500 patients per arm), the expected hazard ratio was 0.82 (95% prediction interval: 0.70–0.95), independent of ethnicity.

Creutzfeldt-Jakob disease with PRNP G114V mutation in a Chinese family

BACKGROUND

Recent evidence has shown clinical phenotypic heterogeneity of inherited prion diseases, even between patients harbouring the same mutation in the PRNP gene.

OBJECTIVE AND METHODS

We collected clinical data from a Chinese family with autosomal dominant dementia and screened the PRNP gene on 28 living members. A stereotactic biopsy of the right frontal lobe of the proband was performed.

RESULTS

The family comprised four affected individuals within two successive generations. The age of onset was in 30 or 40 s, and the duration was about 2-3 years. Clinical features of the affected members included neuropsychiatric disturbances, progressive dementia and extrapyramidal symptoms. Immunostaining for prion protein showed fine granular deposits of PrP(sc) in the neuropil. The PRNP gene analysis demonstrated a heterozygous G114V mutation in 15 family members. The proband was diagnosed as familial Creutzfeldt-Jakob disease (fCJD).

CONCLUSION

This study strengthens the linkage of the G114V mutation to CJD. It supports the worldwide distribution of fCJD despite differences in genetic background.

Circulating cytokine and angiogenic factors as predictive biomarkers of glioblastoma response to aflibercept (VEGF Trap)

2029

Background: Aflibercept is a recombinant fusion protein that scavenges both vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). In a single-arm phase II study (NABTC06–01; NCT00369590 ), a 22% response rate was seen in recurrent glioblastoma patients receiving aflibercept 4 mg/kg iv every 2 weeks. We performed detailed analyses of circulating and urinary cytokine and angiogenic factors to describe the modulation of markers in response to aflibercept and to identify potential predictive markers. Methods: Plasma samples were collected from 31 of 32 enrolled patients at baseline, 24 hours and every 2–4 weeks until progression. Urine samples were collected at baseline and every 4 weeks. Levels of 41 circulating factors were measured using suspension bead multiplex assays (BioRad) or ELISA. Free VEGF and PlGF levels were determined following sample immunodepletion. Baseline and changes in marker levels over time were correlated with response and progression using logistic regression and Cox proportion hazard models. Results: Treatment with aflibercept resulted in significant increases in total VEGF and PlGF at 24 hours and 28 days (p ≤ 0.001). Free VEGF was rapidly sequestered by 24 hours and remained significantly decreased at 28 days (p = 0.001). However, free PlGF levels rose over time and by 28 days were 45-fold higher than baseline (p < 0.001). Additional modulation of 4 factors at 24 hours included decreases in Groα and MIF (p = 0.001) and increases in urinary VEGF and MIP1β (p ≤ 0.001). At 28 days, levels of IL-18 were significantly decreased (p = 0.02) while SCGFβ and urinary VEGF levels increased (both p < 0.02). Comparing baseline biomarker levels between response groups (PD, SD, and PR), patients with lower levels of GROα, HGF, SCGFβ and higher levels of free VEGF were more likely to have a PR (all p < 0.05). Conclusions: In recurrent glioblastoma, aflibercept resulted in rapid and sustained decreases in free VEGF levels. Although greater than 95% of PlGF remained bound, free PlGF levels significantly increased over time. Treatment significantly modulated multiple cytokine and angiogenic factors with striking increases in MIF and SCGFβ. Potential biomarkers predictive of response to aflibercept include Groα, HGF and SCGFβ.

No significant financial relationships to disclose.

Oncolytic adenovirus retargeted to Delta-EGFR induces selective antiglioma activity

The fact that glioblastomas, which are one of the most devastating cancers, frequently express the Delta-EGFR (epithelial growth factor receptor) also called mutant variant III of EGFR (EGFRvIII) suggests that this cancer cell-specific receptor might serve as an ideal target for cancer therapy. To assess its potential as such a target, we constructed an oncolytic adenovirus with Retargeted Infectivity Via EGFR (Delta-24-RIVER) on the backbone of Delta-24. This new oncolytic adenovirus targets, as Delta-24 does, the disrupted Rb pathway in cancer cells; in addition, this adenovirus has also been retargeted through the abrogation of CAR binding (Y477A mutation in adenoviral fiber protein) and insertion of an EGFRvIII-specific binding peptide in the HI loop of the fiber protein. As compared with Delta-24, Delta-24-RIVER induced EGFRvIII-selective cytotoxicity in U-87 MG isogenic cell lines and in tetracycline-inducible EGFRVIII expressing U-251 MG cells. Accordingly, by tittering the viral progeny and examining fiber protein expression in the above cells, we showed that the replication of this new construct also correlated with EGFRvIII expression. Consistently, immunohistochemistry staining of the adenoviral capsid protein hexon in the virus-treated tumors revealed that the virus replicated more efficiently in EGFRvIII-expressing U-87 MG.DeltaEGFR xenografts than in the tumors grown from U-87 MG cells. Importantly, treatment with Delta-24-RIVER prolonged the survival of animals with intracranial xenografts derived from U-87 MG.DeltaEGFR cells. Therefore, our results constitute the first proof of the direct targeting of a cancer-specific receptor using an oncolytic adenovirus.

Angiopoietin-2 decreases vascular endothelial growth factor expression by modulating HIF-1α levels in gliomas

Angiogenesis is thought to depend on a perfectly coordinated balance between endogenous-positive and negative regulatory factors. Of these factors, the vascular endothelial growth factor (VEGF) and angiopoietins (Angs) seem to play an essential role. Recently, we reported the expression of the Ang-natural receptor, Tie2, in neoplastic astrocytic cells within gliomas. Because of the VEGF/Ang2 functional partnership together with the presence of Tie2 in gliomas, we hypothesized a role of Ang2 on the modulation of VEGF levels in these tumors. We examined the effect of Ang2 on VEGF expression in a panel of glioma cells, which showed that Ang2 inhibited VEGF expression at both mRNA and protein levels in Tie2-expressing cells, but not in Tie2-negative cells. VEGF promoter analysis showed that Ang2 regulated VEGF expression at the transcriptional level in relation to a decrease in HIF-1alpha expression and HIF-DNA-binding activity. Tie2 silencing by siRNA rescued the Ang2-mediated downmodulation of VEGF, suggesting an essential role for Tie2 in this regulatory loop. To our knowledge, this is the first report on the role of Ang2/Tie2 in the regulation of HIF-1alpha/VEGF expression, providing additional evidence of the intrinsic coordination that occurs among these factors during angiogenesis.

Combination of the oncolytic adenovirus ICOVIR-5 with chemotherapy provides enhanced anti-glioma effect in vivo

Novel therapies are clearly needed for gliomas, and the combination of oncolytic vectors with chemotherapy possesses a significant hope for the treatment of this malignancy. In addition, combination with chemotherapy allows for lower virus doses to achieve anticancer effect, thus resulting in lower undesirable toxicities due to viral proteins. In this work, we sought to determine whether combination of an oncolytic adenovirus ICOVIR-5, with RAD001 or temozolomide (TMZ) could result in enhanced anti-glioma effect in vivo. We assessed the in vitro cytotoxic effect and replication properties of ICOVIR-5 in combination with RAD001 or TMZ in U87 MG glioma cell line by MTT and TCID(50), respectively. Our data showed that in vitro treatment with RAD001 or TMZ not only interfered with adenovirus replication but, in addition, enhanced its oncolytic properties. To evaluate the in vivo anticancer effect, athymic mice bearing glioma xenografts (5 x 10(5) U87 MG cells/animal) received a single intratumoral injection of ICOVIR-5 (10(7) PFU/animal). RAD001 was given as a regimen of 5 mg/kg 5 days per week until the end of the experiment and TMZ was administered for 5 days at 7.5 mg/kg/mice. Of significance, combination of ICOVIR-5 with RAD001 or TMZ showed a potent anti-glioma effect in vivo, resulting in a dramatic extension of the median animal survival and in 20-40% animals becoming free of disease beyond 90 days.

The absence of a Ca(2+) signal during mouse egg activation can affect parthenogenetic preimplantation development, gene expression patterns, and blastocyst quality

A series of Ca(2+) oscillations during mammalian fertilization is necessary and sufficient to stimulate meiotic resumption and pronuclear formation. It is not known how effectively development continues in the absence of the initial Ca(2+) signal. We have triggered parthenogenetic egg activation with cycloheximide that causes no Ca(2+) increase, with ethanol that causes a single large Ca(2+) increase, or with Sr(2+) that causes Ca(2+) oscillations. Eggs were co-treated with cytochalasin D to make them diploid and they formed pronuclei and two-cell embryos at high rates with each activation treatment. However, far fewer of the embryos that were activated by cycloheximide reached the blastocyst stagecompared tothose activated by Sr(2+) orethanol. Any cycloheximide-activated embryos that reached the blastocyst stage had a smaller inner cell mass number and a greater rate of apoptosis than Sr(2+)-activated embryos. The poor development of cycloheximide-activated embryos was due to the lack of Ca(2+) increase because they developed to blastocyst stages at high rates when co-treated with Sr(2+) or ethanol. Embryos activated by either Sr(2+) or cycloheximide showed similar signs of initial embryonic genome activation (EGA) when measured using a reporter gene. However, microarray analysis of gene expression at the eight-cell stage showed that activation by Sr(2+) leads to a distinct pattern of gene expression from that seen with embryos activated by cycloheximide. These data suggest that activation of mouse eggs in the absence of a Ca(2+) signal does not affect initial parthenogenetic events, but can influence later gene expression and development.

A murine dopamine neuron-specific cDNA library and microarray: increased COX1 expression during methamphetamine neurotoxicity

Due to brain tissue heterogeneity, the molecular genetic profile of any neurotransmitter-specific neuronal subtype is unknown. The purpose of this study was to purify a population of dopamine neurons, construct a cDNA library, and generate an initial gene expression profile and a microarray representative of dopamine neuron transcripts. Ventral mesencephalic dopamine neurons were purified by fluorescent-activated cell sorting from embryonic day 13.5 transgenic mice harboring a 4.5-kb rat tyrosine hydroxylase promoter-lacZ fusion. Nine-hundred sixty dopamine neuron cDNA clones were sequenced and arrayed for use in studies of gene expression changes during methamphetamine neurotoxicity. A neurotoxic dose of methamphetamine produced a greater than twofold up-regulation of the mitochondrial cytochrome c oxidase polypeptide I transcript from adult mouse substantia nigra at 12 h posttreatment. This is the first work to describe a gene expression profile for a neuronal subtype and to identify gene expression changes during methamphetamine neurotoxicity.

Construction of long-transcript enriched cDNA libraries from submicrogram amounts of total RNAs by a universal PCR amplification method

Here we report a novel design of linker primer that allows one to differentially amplify long tracts (average 3.0 kb with size ranges of 1-7 kb) or short DNAs (average 1.5 kb with size ranges of 0.5-3 kb) from a complex mixture. The method allows one to generate cDNA libraries enriched for long transcripts without size selection of insert DNAs. One representative library from newborn kidney includes 70% of clones bearing ATG start codons. A comparable library has been generated from 20 mouse blastocysts, containing only approximately 40 ng of total RNA. This universal PCR amplification scheme can provide a route to isolate very large cDNAs, even if they are expressed at very low levels.

Moderate hypothermia therapy for patients with severe head injury

OBJECTIVE

To evaluate the effect and safety of early moderate hypothermia therapy (MHT) on patients with head injury by using parallel-control test.

METHODS

Thirty patients with severe head injury within 6 hours after accidents were treated by MHT generally for 4-10 days. The other 30 patients with similar head injury treated routinely were enrolled for a parallel-control test. The mortality, morbidity and changes of some neuro-functional indexes as Glasgow Coma Scores, and Glasgow Outcome Scale, levels of endothelin and some other factors of neurobiochemistry in blood plasma were observed. Meanwhile, the dynamic monitoring by transcranial Doppler ultrasonography was conducted in these patients.

RESULTS

The mortality in MHT group was significantly lower than that in control group. MHT not only reduced endothelin but also increased the brain biochemical factors, which were helpful to the protection of neurons in the early brain ischemia after head injury.

CONCLUSIONS

Early MHT can help reduce mortality and morbidity in patients with acute head injury.

Chorea resulting from paraneoplastic striatal encephalitis

A 73 year old man presented with progressive choreic movement and dementia. An antineuronal antibody that recognised a 68 kDa band on a western blot was found in the patient's serum; this antibody immunolabelled neuronal somata in rat brain. Postmortem examination showed a small cell lung cancer and severe neuronal loss with lymphocytic infiltration in the striatum that was more severe in the caudate head. This is thought to be the first pathologically proved case of paraneoplastic chorea with striatal encephalitis.

Genome-wide expression profiling of mid-gestation placenta and embryo using a 15,000 mouse developmental cDNA microarray

cDNA microarray technology has been increasingly used to monitor global gene expression patterns in various tissues and cell types. However, applications to mammalian development have been hampered by the lack of appropriate cDNA collections, particularly for early developmental stages. To overcome this problem, a PCR-based cDNA library construction method was used to derive 52,374 expressed sequence tags from pre- and peri-implantation embryos, embryonic day (E) 12.5 female gonad/mesonephros, and newborn ovary. From these cDNA collections, a microarray representing 15,264 unique genes (78% novel and 22% known) was assembled. In initial applications, the divergence of placental and embryonic gene expression profiles was assessed. At stage E12.5 of development, based on triplicate experiments, 720 genes (6.5%) displayed statistically significant differences in expression between placenta and embryo. Among 289 more highly expressed in placenta, 61 placenta-specific genes encoded, for example, a novel prolactin-like protein. The number of genes highly expressed (and frequently specific) for placenta has thereby been increased 5-fold over the total previously reported, illustrating the potential of the microarrays for tissue-specific gene discovery and analysis of mammalian developmental programs.

Glutamate and aspartate impair memory retention and damage hypothalamic neurons in adult mice

We examined the effects of systemic administration of monosodium glutamate (MSG) or aspartate (ASP) on the memory retention and neuronal damage in the brains of adult mice. Compared with the control mice, a single intraperitoneal injection of either 4.0 mg/g MSG or 0.5 mg/g ASP after acquisition trial significantly shortened the response latency in the passive avoidance test, accompanying by the transient weight loss. Histopathological analysis of the brains of these mice revealed that neurons in the arcuate nucleus of hypothalamus were damaged markedly by MSG (4.0 mg/g) or ASP (0.5 mg/g). Other brain areas including cerebral cortex and hippocampus did not show any pathological changes. These findings suggest that systemic administration of MSG or ASP could impair memory retention and damage hypothalamic neurons in adult mice.

[Experimental study on anti-oxygen and promoting intelligence development of Codonopsis lanceolata in old mice]

The water labyrinth test and determining lipid peroxide (LPO) contents were used to assay the effects of Codonopsis lanceolata on promoting intelligence development and lipid peroxide. The results showed that latent period of old mice in water labyrinth was statistically shorten and the number of mistake of old mice was visibly reduced by drinking extraction of Codonopsis lanceolate 4 g/kg and 8 g/kg. These indicated that mice drinking extraction of Codonopsis lanceloata learned faster that those of drinking water. The contents of LPO in red blood cell and brain of mice and rate drinking extraction of Codonopsis lanceolata were significantly reduced, the activities of superoxide dismutase (SOD) in serum of rat drinking extraction of Codonopsis lanceolata were visibly increased. These presents that the extraction of Codonopsis lanceolata has the role of promoting learning and memory of old animal, its mechanism might be increasing SOD activity and decreasing LPO level.

Prevention by minaprine of ischemic neuronal damage and memory impairment in Mongolian gerbils

This study examines the effect of the psychotropic drug minaprine on memory impairment in Mongolian gerbils subjected to a 5-min bilateral common carotid artery occlusion, as assessed by their performance in an 8-arm radial maze task. Gerbils were initially trained on the 8-arm radial maze until their mean error was 0-1 for 5 days. This task was repeated before the ischemia was performed and again 7 days after it. Then the animals were immediately sacrificed for histopathological examination. Severe memory impairment occurred in the control gerbils; whereas when minaprine 75 mg/kg was given orally 30 min before the 5-min occlusion, memory impairment was significantly reduced. Histopathological analysis of the control gerbils showed nearly complete loss of the pyramidal neurons in the CA1 region of the hippocampus, whereas the minaprine-treated gerbils showed complete preservation of the pyramidal neurons. These findings suggest that minaprine has memory-impairment-prevention and neuroprotective effects against short-term ischemia in gerbils.

A point mutation in the putative TATA box, detected in nondiseased individuals and patients with hereditary breast cancer, decreases promoter activity of the 17 beta-hydroxysteroid dehydrogenase type 1 gene 2 (EDH17B2) in vitro

EDH17B2, the gene encoding 17 beta-hydroxysteroid dehydrogenase type 1, has been suggested as a candidate for the familial breast cancer gene, BRCA1, located on 17q12-q21. We analyzed the promoter region of EDH17B2 in DNA from 20 control individuals and 40 patients with familial breast cancer. Two frequent (designated vI and vIII) and two rare (vII and vIV) nucleotide variations were present in both the breast cancer patients and the controls, except the alteration vII, which was found only in one patient. Although the data do not support the identification of EDH17B2 as the BRCA1 gene, it is of interest that point mutation vIV (A-->C) was located in the putative TATA box of the EDH17B2 gene. Reporter gene analyses showed that the mutation vIV decreases EDH17B2 promoter activity by an average of 45% in in vitro assays, suggesting that nucleotide A at position -27 is significant for efficient transcription.

Functional analysis of the Arg91Gln substitution in the factor VIII binding domain of von Willebrand factor demonstrates variable phenotypic expression

An Arg91Gln substitution in the mature von Willebrand factor (vWF) has been associated with defective binding of vWF to factor VIII (FVIII). We studied four families with members initially classified as having type I von Willebrand disease (vWD) who were either homozygous or heterozygous for the Arg91Gln change. The first family was the original case described by Nishino et al. (1) where three members were homozygous for the Gln91 allele. They had a low FVIII coagulant activity:vWF antigen (VIIIC:vWFAg) ratio, from 0.29 to 0.44, and the ability of their plasma vWF to bind FVIII was markedly decreased. All the heterozygous members had normal vWF and FVIII levels but the capacity of their plasma vWF to bind FVIII was reduced and intermediate between the homozygous members and normals. The affected individual from the second family was heterozygous for the Gln91 allele and demonstrated a VIIIC:vWFAg ratio of 0.98. The FVIII binding assay confirmed the heterozygous status indicating that the moderately low levels of vWF were due to reduced expression of both alleles. The propositus from the third family was also heterozygous and had below normal levels of vWF as well as a low VIIIC:vWFAg ratio of 0.34; however, FVIII binding to her plasma vWF was similar to that of the homozygous individuals suggesting that Gln91-vWF was the major circulating form. Her daughter who has type I vWD inherited the allele without the Gln91 mutation indicating that the expression of this allele was indeed impaired. The heterozygous patient in the fourth family had a vWF level of 24 U/dl but an VIIIC:vWFAg ratio greater than 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of a molecular defect in 40 of 44 patients with haemophilia B by PCR and denaturing gradient gel electrophoresis

Oligonucleotides were computer designed to amplify by the polymerase chain reaction (PCR) the coding region, splice junctions, 112 bp of the 5' flanking region and 279 bp surrounding the polyadenylation site of the factor IX gene for analysis by denaturing gradient gel electrophoresis (DGGE). Forty-four unselected haemophilia B patients were studied of whom 24 had severe haemophilia and 20 had a mild to moderate form of the disease. Potential mutations were identified in 40 (91%) of the 44 cases. A defect could not be detected in three severe and one mild haemophiliac by DGGE analysis and direct sequencing of all the PCR fragments from these patients revealed no nucleotide alteration supporting the DGGE results. A total of 37 point mutations, two complete gene deletions and a duplication of 26 bp were found. The 37 point mutations included 35 single nucleotide substitutions, a deletion and an insertion of one nucleotide. The 35 single nucleotide substitutions included 26 missense mutations, seven nonsense mutations, a G (-6) to A transition in the promoter region and a G (30154) to A transition within the donor splice site of the last intron. Fifteen of these nucleotide substitutions involved CpG dinucleotides. Fifteen point mutations were found at codons where nucleotide substitutions had not been detected before. An insertion of a single nucleotide T at position 6370 and deletion of a G at nucleotide 30845 resulted in frameshift mutations creating stop codons at amino acid positions -2 and 250, respectively. A duplication of 26 bp (17747-17772) in exon V was found in a severe haemophilia patient resulting in a termination codon in exon VI. The detection of the mutation by the combined use of PCR, DGGE and direct sequencing was important for carrier diagnosis of 20 families with no prior history of haemophilia B.