The Pennsylvania hemophilia program 1973-1978

Identification of the Intron 22 and Intron 1 Inversions of the Factor VIII Gene in Iraqi Kurdish Patients With Hemophilia A

Hemophilia A (HA) is a severe coagulation disorder affecting 1 in 5000 to 10 000 male births. In severe cases, the most deleterious large DNA rearrangements are inversions of intron 22 (Inv22) and intron 1 (Inv1) of the factor VIII (FVIII) gene. These account for 40% to 50% and 1% to 5% of all causative mutations, respectively. Nevertheless, no genetic analysis to identify the actual causative mutation of FVIII, particularly Inv22 and Inv1, among Iraqi Kurdish hemophiliacs has been performed. In this study, we aimed to genotype Inv22 and Inv1 of the FVIII gene in our patients with HA and reveal the genotype/phenotype correlation with the inversion mutations and their role as a risk factor for the development of inhibitors. Analyses of the Inv22 and Inv1 mutations in 80 Iraqi Kurdish patients with HA (60 severe, 18 moderate, and 2 mild) were performed using the inverse shifting–polymerase chain reaction (IS-PCR) method. In severe cases, 46.7% (28/60) had Inv22 and 3.3% (2/60) had Inv1. The genotype/phenotype relation of Inv22 and Inv1 illustrated a statistically significant association (P = .012) between disease severity and inversion mutations. Slightly more patients with Inv22 (39%) developed inhibitors than those without Inv22 (28%; odds ratio = 1.65, 95% confidence interval = 0.56-4.87, P = .361). Inv22 is a major cause of severe HA in Iraqi Kurdish patients, and IS-PCR is a rapid, robust, and effective method that can be applied for carrier detection and prenatal diagnosis of HA in developing countries.

Risk factors associated with inhibitor development in Chinese patients with haemophilia B

INTRODUCTION

Inhibitor development is a severe complication of factor IX substitution treatment for haemophilia B (HB). Current research examined the association between inhibitor development and F9 genotypes and polymorphisms in immune response genes in Chinese HB patients.

MATERIALS AND METHODS

11 inhibitor-positive HB patients and 41 inhibitor-negative HB patients were enrolled. Direct sequencing, copy number variation (CNV) detection and fragment length analysis were applied to identify F9 genotypes and 15 polymorphisms in immune response genes.

RESULTS

7 patients developed high titer inhibitors, with 5 of them having histories of consecutive exposure to FIX products on demand for at least 5 days. Allergic reactions/anaphylaxis to prothrombin complex concentrates (PCC) occurred in 3 patients before inhibitors were detected. Five nonsense mutations (E54X, R75X, Q185X, R298X and R379X), two large deletions (E1~6del and E1~8del) and one missense mutation (S411G) were identified in patients with inhibitors. Missense mutations had a low odds ratio for FIX inhibitors development (IOR) of 0.078 (P = 0.02), while nonsense mutation presented a high IOR of 8.500 (P = 0.0044). The frequency of allele T in CD44(95102) (A/T) was significantly higher in inhibitor-negative patients, with OR of 0.324 (P = 0.04).

CONCLUSIONS

Nonsense mutations conferred a higher risk for while allele T in CD44(95102) (A/T) might play a protective role against inhibitor development in Chinese HB patients.

A Polymorphism in the IL-5 Gene is Associated with Inhibitor Development in Severe Hemophilia A Patients

OBJECTIVE

A severe complication in the replacement therapy of hemophilia A (HA) patients is the development of alloantibodies (inhibitors) against factor VIII, which neutralizes the substituted factor. The primary genetic risk factors influencing the development of inhibitors are F8 gene mutations. Interleukins and cytokines that are involved in the regulation of B-lymphocyte development are other possible targets as genetic risk factors. This study assesses the possible involvement of 9 selected single nucleotide gene polymorphisms (SNPs) with interleukins (IL-4, IL-5, and IL-10), transforming growth factor beta 1 (TGF-β1), and interferon gamma (IFN-γ) in inhibitor development in severely affected HA patients carrying a null mutation in the F8 gene.

MATERIALS AND METHODS

A total of 173 HA patients were screened for intron 22 inversion and null mutations (nonsense and deletions). Genotyping of a total of 9 SNPs in genes IL-4, IL-5, IL-10, TGF-β1, and IFN-γ in 103 patients and 100 healthy individuals was carried out.

RESULTS

An association analysis between 42 inhibitor (+) and 61 inhibitor (-) patients showed a significant association with the T allele of rs2069812 in the IL-5 gene promoter and patients with inhibitors (p=0.0251). The TT genotype was also significantly associated with this group with a p-value of 0.0082, odds ratio of about 7, and confidence interval of over 90%, suggesting that it is the recessive susceptibility allele and that the C allele is the dominant protective allele.

CONCLUSION

The lack of other variants in the IL-5 gene of patients and controls suggests that rs2069812 may be a regulatory SNP and may have a role in B-lymphocyte development, constituting a genetic risk factor in antibody development.

Molecular characterization of 16 hemophilia B families in Aragon, Spain

Molecular characterization of hemophilia B at gene level has become an indispensable tool for a proper genetic counseling in carriers and for a closer surveillance of inhibitor development in several severe forms. Our study was aimed at characterizing the molecular defects in the factor IX (FIX) gene in hemophilia B families in Aragon, a center-east region of Spain. Direct sequencing of all regions of likely functional significance of the FIX gene was performed in the screened 18 hemophilia B families. Quantitative techniques, such as multiplex ligation-dependent prove amplification reaction, were carried out only in patients in whom no mutation was found. We have identified the molecular events responsible for hemophilia B in 16 unrelated families (eight with mild hemophilia B and eight with severe hemophilia B). Out of all families studied, we have found 14 missense mutations and two nonsense mutations; still we were unsuccessful in determining the genetic defects in two severe and unrelated families. Of the 16 characterized mutations, 14 of them lie in the protease domain in which one mutation, A233T, was surprisingly found in three unrelated families. We also report and discuss the pathogenicity of F314L, a novel mutation found in the protease domain. Our molecular data reflect a notable heterogeneity of the mutational spectrum mainly in the protease domain of FIX. This is the first mutation report on the disease in Aragon, Spain.

Analysis of five polymorphic DNA markers for indirect genetic diagnosis of haemophilia A in the Brazilian population

Hemophilia A is an X-linked, inherited, bleeding disorder caused by the partial or total inactivity of the coagulation factor VIII (FVIII). Due to difficulties in the direct recognition of the disease-associated mutation in the F8 gene, indirect diagnosis using polymorphic markers located inside or close to the gene is used as an alternative for determining the segregation of the mutant gene within families and thus for detecting carrier individuals and/or assisting in prenatal diagnosis. This study characterizes the allelic and haplotype frequencies, genetic diversity, population differentiation and linkage disequilibrium of five microsatellites (F8Int1, F8Int13, F8Int22, F8Int25.3 and IKBKG) in samples of healthy individuals from São Paulo, Rio Grande do Sul and Pernambuco and of patients from São Paulo with haemophilia A to determine the degree of informativeness of these microsatellites for diagnostic purposes. The interpopulational diversity parameters highlight the differences among the analyzed population samples. Regional differences in allelic frequencies must be taken into account when conducting indirect diagnosis of haemophilia A. With the exception of IKBKG, all of the microsatellites presented high heterozygosity levels. Using the markers described, diagnosis was possible in 10 of 11 families. The F8Int22, F8Int1, F8Int13, F8Int25.3 and IKBKG microsatellites were informative in seven, six, five and two of the cases, respectively, demonstrating the effectiveness of using these microsatellites in prenatal diagnosis and in carrier identification in the Brazilian population.

A study of variations in the reported haemophilia A prevalence around the world

The objectives of this paper were to study the reported haemophilia A prevalence (per 100 000 males) on a country-by-country basis and address the following: Does the reported prevalence of haemophilia A vary by national economies? We collected prevalence data for 106 countries from the World Federation of Hemophilia (WFH) annual global surveys and the literature. We found that the reported haemophilia A prevalence varied considerably among countries, even among the wealthiest of countries. The prevalence (per 100 000 males) for high income countries was 12.8 +/- 6.0 (mean +/- SD) whereas it was 6.6 +/- 4.8 for the rest of the world. Within a country, there was a strong trend of increasing prevalence over time--the prevalence for Canada ranged from 10.2 in 1989 to 14.2 in 2008 (R = 0.94 and P < 0.001) and for the United Kingdom it ranged from 9.3 in 1974 to 21.6 in 2006 (R = 0.94 and P < 0.001). Prevalence data reported from the WFH compared well with prevalence data from the literature. Patient registries generally provided the highest quality of prevalence data. The lack of accurate country-specific prevalence data has constrained planning efforts for the treatment and care of people with haemophilia A. With improved information, healthcare agencies can assess budgetary needs to develop better diagnostic and treatment facilities for affected patients and families and work to ensure adequate supplies of factor VIII concentrates for treatment. In addition, this information can help manufacturers plan the production of concentrates and prevent future shortages.

Factor 8 (F8) gene mutation profile of Turkish hemophilia A patients with inhibitors

Factor VIII (FVIII) replacement therapy is ineffective in hemophilia A patients who develop alloantibodies (inhibitors) against FVIII. The type of factor 8 (F8) gene mutation, genes in the major histocompatibility complex loci, and also polymorphisms in IL-10 and tumor necrosis factor-alpha are the major predisposing factors for inhibitor formation. The present study was initiated to reveal the F8 gene mutation profile of 30 severely affected high-responder patients with inhibitor levels of more than 5 Bethesda U (BU)/ml and four low-responder patients with inhibitors less than 5 BU/ml. Southern blot and PCR analysis were performed to detect intron 22 and intron 1 inversions, respectively. Point mutations were screened by DNA sequence analysis of all coding regions, intron/exon boundaries, promoter and 3' UTR regions of the F8 gene. The prevalent mutation was the intron 22 inversion among the high-responder patients followed by large deletions, small deletions, and nonsense mutations. Only one missense and one splicing error mutation was seen. Among the low-responder patients, three single nucleotide deletions and one intron 22 inversion were found. All mutation types detected were in agreement with the severe hemophilia A phenotype, most likely leading to a deficiency of and predisposition to the development of alloantibodies against FVIII. It is seen that Turkish hemophilia A patients with major molecular defects have a higher possibility of developing inhibitors.

Factor VIII-Intron 1 Inversion of Hemophilia A Patients In West Anatolia

Hemophilia A (HA) is a hereditary, life-threatening and disabling disorder. In this study, we have examined 61 unrelated HA patients in order to identify the incidence of the intron 1 factor VIII (FVIII) gene inversion in the West Anatolian population. According to the results of DNA analyses of the 61 HA patients, no intron 1 inversion of the FVIII gene was found.

Predicting severity of haemophilia A and B splicing mutations by information analysis

Bleeding symptoms and clotting activity vary among mutations that alter mRNA splicing of either the factor VIII or factor IX genes. We analyzed splicing mutations in both genes for changes in individual information (R(i), in bits) involving both donor or acceptor sites. Mutations with low or negative R(i) values (<2.4 bits) or significant changes in R(i) (DeltaR(i) > or = 7 bits) exhibited either reduced protein activity, increased clotting time and bleeding frequency and were predictive of severe disease. Thus, information analysis of splicing mutations may be useful in predicting phenotypes in hemophilia.

Molecular pathology of haemophilia B in Turkish patients: identification of a large deletion and 33 independent point mutations

Heterogeneous mutations in the coagulation factor IX (FIX) gene result in a bleeding tendency known as haemophilia B. The haemophilia B mutation database has a total of 2353 patient entries, including 10 of the estimated 1000 Turkish patients. In this study, a more comprehensive analysis of the molecular pathology of haemophilia B in Turkey revealed one large deletion and 33 point mutations in the FIX gene of 34 unrelated patients. Haplotype analysis using six polymorphic sites showed that the mutations identified in a total of 45 patients occurred on 13 different haplotypes and that each mutation was family specific.

Molecular pathology of haemophilia A in Turkish patients: identification of 36 independent mutations

Haemophilia A is an X-linked recessive bleeding disorder caused by heterogeneous mutations in the factor VIII gene. In an attempt to reveal the molecular pathology of Turkish haemophilia A patients, the coding sequence of the gene, excluding a large portion of exon 14, was amplified from genomic DNA and subjected to denaturing gradient gel electrophoresis prior to DNA sequencing. Fifty-nine haemophilia A patients were included in the study with severe, moderate and mild phenotypes observed in 24, 15 and 16 patients, respectively. Factor VIII activity and clinical phenotypes were not available for four patients. A total of 36 independent mutations were found, with a mutation detection efficacy of 61%. The mutations that were reported for the first time include 20 point mutations, one 8-bp insertion (TCAAGATA) in exon 4 and one large deletion greater than 2.8 kb involving exon 14. The novel point mutations were composed of three nonsense (Ser681Ter, Cys2021Ter and Gln2113Ter), one splicing error (IVS-1G-->A), 15 missense mutations (Lys48Asn; Leu-98Phe; Thr118Ala; Cys248Tyr; Glu456Lys; Asp560Ala; Tyr664Cys; Phe679Leu; Gly691Trp; Asp1769His; Val1857Leu; Gly2026Gln; Arg2163Pro; Asp2288Ala; and Arg2304Leu) and a T deletion in exon 25 that caused a frameshift followed by a stop codon. All missense mutations except Val1857Leu, which maintained a conserved nonpolar R group, occurred at amino acids conserved among four species and were most probably pathogenic. In addition, two sequence changes (IVS3-9C-->T) and (Leu2230Leu) were also detected in patients carrying Val1857Leu and Phe679Leu missense mutations, respectively. Identification of mutation origins in eight sporadic cases revealed an equal sex ratio of mutations.

Frequency of recent retrotransposition events in the human factor IX gene

Two germline retrotransposition mutations of recent origin were observed in 727 independent mutations (0.28%) in the human factor IX gene (F9) of patients with hemophilia B: 1) a 279 bp insertion in exon H originating from an Alu family of short interspersed elements not previously known to be active and, 2) a 463 bp insertion in exon E of a LINE1 element originating in the maternal grandmother. If the rates of recent germline mutation in F9 are typical of the genome, a retrotransposition event is estimated to occur somewhere in the genome of about one in every 17 children born. Analysis of other estimates for retrotransposition frequency and overall mutation rates suggests that the actual rate of retrotransposition is likely to be in the range of one in every 2.4 to 28 live births.

Germline mutations in Peruvian patients with hemophilia B: pattern of mutation in AmerIndians is similar to the putative endogenous germline pattern

Exogenous (e.g., environmental) mutagens produce characteristic patterns of mutation. In contrast, endogenous mutation processes likely are associated with an invariant pattern of mutation. Analysis of factor IX gene mutations among large samples of hemophilia B patients from multiple, widely divergent geographic and ethnic populations reveals a remarkably constant mutational pattern, suggesting that the primary germline mutational process results from endogenous processes rather than environmental mutagens. To test this hypothesis further, we have initiated a study of hemophilia B patients from Peru because relatively large populations of AmerIndians can be found with low admixtures of other races. To determine if the factor IX (FIX) germline mutational pattern in AmerIndians differs from the common and putative endogenous pattern, FIX gene mutations were characterized in an initial sample of 10 AmerIndian Peruvian patients with hemophilia B. A minimum of 2.2 kb of the FIX gene was examined by PCR and direct sequencing of all eight exons, the splice junctions, and the promoter region. The pattern of germline mutation in AmerIndians was similar to the pattern of FIX germline mutations from larger U. S. Caucasian or Mexican Hispanic samples (P=0.55 and 0.63, respectively). The similar pattern in this initial sample of the Peru AmerIndian population provides additional support for the inference that the FIX germline mutational pattern results from predominantly endogenous processes rather than exogenous mutagens.

Reported in vivo splice-site mutations in the factor IX gene: severity of splicing defects and a hypothesis for predicting deleterious splice donor mutations

Small consensus sequences have been defined for RNA splicing, but questions about splicing in humans remain unanswered. Analysis of germline mutations in the factor IX gene offers a highly advantageous system for studying the mutational process in humans. In a sample of 860 families with hemophilia B, 9% of independent mutations are likely to disrupt splicing as their primary mode of action. This includes 26 splicing mutations reported herein. When combined with the factor IX splice mutations reported by others, at least 104 independent mutations have been observed, 80 of which are single base substitutions within the splice donor and splice acceptor consensus sequences. After analysis of these mutations, the following inferences emerge: (1) the susceptibility of a splice donor sequence to deleterious mutation depends on the degree of similarity with the donor consensus sequence, suggesting a simple "5-6 hypothesis" for predicting deleterious vs. neutral mutations; (2) the great majority of mutations that disrupt the splice donor or splice acceptor sequences result in at least a 100-fold decrement in factor IX coagulant activity, indicating that the mutations at these sites generally function as an on/off switch; (3) mutations that create cryptic splice junctions or that shorten but do not interrupt the polypyrimidine tract in the splice acceptor sequence can reduce splicing by a variable amount; and (4) there are thousands of potential donor-acceptor consensus sequence combinations in the 38-kb factor IX gene region apparently not reduced by evolutionary selective pressure, presenting an apparent paradox; i.e., mutations in the donor and acceptor consensus sequences at intron/exon splice junctions can dramatically alter normal splicing, yet, appropriately spaced, good matches to the consensus sequences do not predispose to significant amounts of alternative splicing.

Intron 22 inversions in the Turkish haemophilia A patients: prevalence and haplotype analysis

In about half of the severe haemophilia A cases, the disease is caused by an inversion that split the F.VIII gene into two parts separated by approximately 300-400 kb. Herein, we show that in the Turkish population this inversion mutation accounts for 29% of 141 haemophilia A cases and 42% of severe cases. Most of the inversions are of the distal type (72%) whereas nine were of the proximal type (28%). Haplotype analysis using 4 markers in the F.VIII gene did not reveal a single haplotype associated with the inversion. However, the pre- valence of one haplotype: HindIII (-) - Int13 (CA)20 - Int22 (CA + CT)26 - XbaI (-) is higher in the inversion patients. Since founder effect is excluded for the inversion patients, our results suggest that some as yet unknown factor(s) may make these alleles more prone for the inversion. However, a bias due to the low number of studied cases cannot be excluded.

Haemophilia B Brandenberg-type promoter mutation

We report the second confirmed case of the haemophilia B 'Brandenberg' phenotype. At the time of testing, patient HB530 was a 17-year-old post-puberty male with a persistent, clinically severe bleeding disorder and markedly reduced plasma procoagulant factor IX activity (< 1%). Sequencing studies revealed a G-->A transition at bp - 26 within the promoter region of the factor IX gene. This case report confirms the observation that not all patients with promoter mutations improve after puberty and supports the hypothesis that bp - 26 is a critical binding site within the factor IX gene promoter region for both constitutive as well as androgen-inducible transcription factors.

Hemophilia home treatment. Economic analysis and implications for health policy

This analysis describes the development of technology for home self-infusion of factor VII in the treatment of hemophilia and its clinical, economic, and social consequences, and uses the case study of such home care treatment to illustrate the potentials and pitfalls of formal economic analyses of programs to treat chronically ill children. A comprehensive review of all original data on hemophilia programs, their related costs, and outcomes, conducted from 1966 through 1993, examined the economic outcomes for two hypothetical cohorts, one aged 0-4 years and the other aged 30-34 years. Including the measurement of treatment effects on the productivity of parental caregivers substantially increases the benefit-cost relationship of an intervention directed at chronically ill children. Increased economic productivity and societal return resulting from such a program for young adults exceeds those for a cohort of children, primarily due to assumptions related to discounting. However, estimation of quality-adjusted life years favors the younger age cohort, since children survive for a longer period of time and with each year survived comes a higher quality of life. Unlike simpler instances in which economic benefits can be shown to outweigh resource costs, policy decisions concerning services for chronically ill children raise an additional set of complex analytic issues. Inclusion of the benefits in productivity experienced by family caregivers provides an important added dimension to such analyses. The development of cost-benefit or cost-effectiveness analyses of these programs illustrates the importance of careful measurement of outcomes and explicit statements of underlying assumptions. Such an analysis of home care for children with hemophilia therefore demonstrates both the strengths and the limitations of this approach.

How precisely can data from transgenic mouse mutation-detection systems be extrapolated to humans?: lesions from the human factor IX gene

Transgenic mutation-detection systems have been pioneered in mice, but the approach is applicable to any species in which transgenic animals can be generated. The observed mutations seen in mutation-detection systems are influenced by the underlying pattern of mutation, i.e., the mutational pattern that occurs in wild-type organisms in endogenous segments of DNA that are not under selective pressure. Unfortunately, the biology of most genes and assays markedly skew the underlying pattern of mutation. Herein, we raise multiple issues that must be addressed in order to estimate the underlying pattern of spontaneous mutation from transgenic mouse mutation-detection systems. If these issues can be addressed, the underlying pattern of spontaneous mutation can then be deduced for multiple cell types and for transgenes integrated into different parts of the genome. Even though transgenic methodology cannot be applied directly to humans, it is likely that comparable data on the underlying pattern of spontaneous mutation will be available in humans. Such data are currently available for germline mutations in the factor IX gene. These data are reviewed because of their relevance to two of the multiple issues that must be addressed in transgenic mouse mutation-detection systems: (1) How can the underlying pattern of mutation be deduced from the observed pattern? and (2) How similar are the underlying patterns of mutation in humans and in mice? The analysis of recent germ-line mutation in the factor IX gene yield estimates of the mutation rates per base pair per generation. In brief, the mutation rates vary from 0.037 x 10(-10) for deletions (> 20 bp) to 360 x 10(-10) for transitions at the dinucleotide CpG. If these mutation rates are extrapolated to the entire genome, the aggregate mutation rate is estimated to be 36 x 10(-10). This implies that the diploid genome of each person contains about 21 de novo mutations. In the future, the underlying pattern of spontaneous mutation will be deduced for multiple human genes and these will serve as benchmarks to assess the similarity of the mutational process in humans and in mice.

The pattern of spontaneous germ-line mutation: relative rates of mutation at or near CpG dinucleotides in the factor IX gene

Mutations at CpG dinucleotides were delineated in the factor IX gene of 38 hemophilia B patients. When transitions at CpG were considered with those previously reported by us and those compiled in the factor IX mutation database, the following patterns emerged. Many CpG sites were mutated with high frequency, while two CpG sites were infrequently mutated (R29-->Q and R116-->TGA). Of the 6 possible nonsense mutations and the 14 missense mutations that would produce a nonconservative change at conserved amino acids, all have been observed to cause hemophilia B except A-10-->T and R338-->Q. By contrast, none of the 6 missense changes at nonconserved amino acids have been observed to cause hemophilia B. At those CpG sites that are frequently mutated, the rate of transitions is estimated to be 20-fold higher than transitions at non-CpG sites. Point mutations in close proximity to CpG dinucleotides did not seem elevated.

Evidence that descendants of three founders constitute about 25% of hemophilia B in the United States

In our sample of 160 consecutive Caucasian hemophiliacs, 14 (9%) had a G----A transition at bp 10,430 that substitutes serine for glycine 60 in the first EGF domain of the factor IX molecule. Each of these hemophiliacs had clinically mild disease. Haplotype data and familial pedigrees indicate that 12 of these hemophiliacs are likely to be related to a common ancestor. The 13th and 14th patients possess different haplotypes and thus represent independent origins of the mutation. In addition, we have screened these 160 hemophiliacs for the previously reported mutations resulting from founder effects at IIe397----Thr and Thr296----Met. Herein we report an additional nine hemophiliacs with the mutant Thr397 allele and five additional hemophiliacs with the mutant Met296 allele. Haplotype data for these 14 hemophiliacs support the original founder effect hypotheses for these mutations. In total, the above three mutations are found in 44 of the 160 seemingly unrelated Caucasian hemophiliacs (28%). The sample includes patients from all regions of the United States and Ontario, Canada. Descendants of these three founders comprise approximately two-thirds of the missense mutations found in our sample of Caucasian hemophiliacs with clinically mild disease.

A past mutation at isoleucine 397 is now a common cause of moderate/mild haemophilia B

Of the factor IX sequence changes that we have identified in 65 consecutive males with haemophilia B, 11 (17%) are the same mutation. This mutation is a T----C transition at base 31311 which substitutes threonine for isoleucine397 (ile397) in the factor IX molecule. The 11 patients are of Western European descent and have the same haplotype: Hinf1 (-), Xmn1 (-), Taq1 (-), BamH1 (+), Malmö allele = thr148. The frequency of this haplotype was estimated and the probability of the same mutation occurring independently 11 times in this haplotype was miniscule. We conclude that these patients have a common ancestor despite the lack of overlapping pedigrees. The clinical symptoms of the disease were consistently moderate/mild in these 11 patients, whereas factor IX coagulation values obtained from the medical records varied more than sixfold between individuals. However, when plasma from five individuals was assayed by the same laboratory concurrently, the values varied less than twofold. Thus, in routine practice, clinical severity may correlate better with the presence of a given mutation than the factor IX coagulant activity. The high frequency of the mutation at ile397 indicates that carrier testing in families of Northern European descent with moderate/mild haemophilia B can be expedited by first determining whether this particular mutation is present. We demonstrate here that the technique of polymerase chain reaction (PCR) amplification of specific alleles (PASA) can be used to rapidly perform carrier testing in families with the ile397 mutation.

Educational and vocational achievement among hemophiliacs: the Pennsylvania experience

A survey of the educational and vocational achievement of the 423 adult hemophiliacs registered with the Commonwealth of Pennsylvania Hemophilia Program found that the hemophiliacs were significantly better educated yet somewhat less frequently employed than their age-matched cohorts in the Pennsylvania population. The discrepancy between educational achievement among hemophiliacs and their ability to obtain employment was most apparent for subjects with severe disease. This suggests that severity of disease remains a significant barrier to vocational achievement for some hemophiliacs, despite comprehensive care and their overall educational gains. Possible reasons for this discrepancy in achievement are discussed and the need for greater emphasis on research and the development of vocational services is stressed.

Congenital bleeding disorders: hemophilia and von Willebrand's disease

Treatment of hemophilia and von Willebrand's disease has become easier in recent years because of the development of more effective factor replacement products. The median age and the life expectancy of patients with hemophilia have risen markedly, as has the median age at death.