Mutations in the activin receptor-like kinase 1 gene in hereditary haemorrhagic telangiectasia type 2.

Hereditary haemorrhagic telangiectasia, or Osler-Rendu-Weber (ORW) syndrome, is an autosomal dominant vascular dysplasia. So far, two loci have been demonstrated for ORW. Linkage studies established an ORW locus at chromosome 9q3; endoglin was subsequently identified as the ORW1 gene. A second locus, designated ORW2, was mapped to chromosome 12. Here we report a new 4 cM interval for ORW2 that does not overlap with any previously defined. A 1.38-Mb YAC contig spans the entire interval. It includes the activin receptor like kinase 1 gene (ACVRLK1 or ALK1), a member of the serine-threonine kinase receptor family expressed in endothelium. We report three mutations in the coding sequence of the ALK1 gene in those families which show linkage of the ORW phenotype to chromosome 12. Our data suggest a critical role for ALK1 in the control of blood vessel development or repair.

International guidelines for the diagnosis and management of hereditary haemorrhagic telangiectasia.

BACKGROUND: HHT is an autosomal dominant disease with an estimated prevalence of at least 1/5000 which can frequently be complicated by the presence of clinically significant arteriovenous malformations in the brain, lung, gastrointestinal tract and liver. HHT is under-diagnosed and families may be unaware of the available screening and treatment, leading to unnecessary stroke and life-threatening hemorrhage in children and adults. OBJECTIVE: The goal of this international HHT guidelines process was to develop evidence-informed consensus guidelines regarding the diagnosis of HHT and the prevention of HHT-related complications and treatment of symptomatic disease. METHODS: The overall guidelines process was developed using the AGREE framework, using a systematic search strategy and literature retrieval with incorporation of expert evidence in a structured consensus process where published literature was lacking. The Guidelines Working Group included experts (clinical and genetic) from eleven countries, in all aspects of HHT, guidelines methodologists, health care workers, health care administrators, HHT clinic staff, medical trainees, patient advocacy representatives and patients with HHT. The Working Group determined clinically relevant questions during the pre-conference process. The literature search was conducted using the OVID MEDLINE database, from 1966 to October 2006. The Working Group subsequently convened at the Guidelines Conference to partake in a structured consensus process using the evidence tables generated from the systematic searches. RESULTS: The outcome of the conference was the generation of 33 recommendations for the diagnosis and management of HHT, with at least 80% agreement amongst the expert panel for 30 of the 33 recommendations.

Reported cardiac phenotypes in hereditary hemorrhagic telangiectasia emphasize burdens from arrhythmias, anemia and its treatments, but suggest reduced rates of myocardial infarction.

INTRODUCTION: Cardiac phenotypes should be pronounced in hereditary hemorrhagic telangiectasia (HHT) due to frequent systemic arteriovenous malformations (AVMs), iron deficiency anemia, hypoxemia, hyperdynamic circulations, venous thromboemboli, and paradoxical emboli through pulmonary AVMs. METHODS/RESULTS: In an international survey, 1025 respondents (median age 55years) met HHT diagnostic criteria: 942 (91.9%) reported nosebleeds, 452 (44.1%) at least daily. AVMs were commonly reported in pulmonary (544, 53%), hepatic (194, 18.9%) and/or cerebral (92, 9.0%) circulations. 770/1025 (75%) had used iron tablets, 256 (25.0%) intravenous iron, and 374 (36.5%) received blood transfusions. Arrhythmias were reported by 113/1025 (11%, including 44 (4.3%) with atrial fibrillation), angina by 36 (3.5%), and cardiac failure by 26 (2.5%). In multivariate logistic regression, these phenotypes were associated with hepatic AVMs/pulmonary hypertension (relatively interchangeable variables), blood transfusions, and intravenous iron. Cardiac insufficiency/failure often provokes intensive anemia treatments, but associations with arrhythmias, particularly with a greater transfusion burden, were less easy to explain. Myocardial infarction (23/1025; 2.2%), and abnormal coronary angiogram (≤31/76, ≤54%) rates appeared low. Provocative preliminary data were obtained including HHT-affected respondents' parents and grandparents in whom HHT could be confidently assigned, or excluded based on autosomal dominant inheritance patterns: in crude and survival analyses, myocardial infarctions were reported less frequently for individuals with HHT, particularly for males (p=0.001). CONCLUSION: Arrhythmias are the most common cardiac phenotype in HHT, and likely to be aggravated by iron deficiency anemia, its treatments, and/or high output states due to AVMs. Myocardial infarction rates may be reduced in this apparently high risk population.

Clouston syndrome (hidrotic ectodermal dysplasia) is not linked to keratin gene clusters on chromosomes 12 and 17.

Clouston syndrome is an hidrotic form of ectodermal dysplasia, inherited as an autosomal dominant trait with high penetrance. The main features of the disorder are alopecia, severe dystrophy of the nails, and palmoplantar hyperkeratosis. A molecular abnormality of keratin has long been hypothesized to be the basic defect in this disorder. We have performed linkage analyses between the disorder and markers close to the keratin gene clusters on chromosomes 12 and 17 and have excluded linkage to these candidate regions in three apparently unrelated families. In addition, linkage has been excluded to four other candidate regions including 1q2l, 17q23-qter, 18q2l, and 2Oql2. These data indicate that Clouston syndrome is not due to a defect in keratin or in a subset of keratin-associated proteins.

Confirmation of linkage of Clouston syndrome (hidrotic ectodermal dysplasia) to 13q11-q12.1 with evidence for multiple independent mutations.

Clouston syndrome (hidrotic ectodermal dysplasia) is an autosomal dominant disorder characterized by the triad of nail dystrophy, alopecia, and palmoplantar hyperkeratosis. Recently, linkage of a Clouston syndrome locus to chromosome 13q11-q12.1 was reported in eight families of French-Canadian descent. We have confirmed linkage to this region in four additional families: two of French-Canadian descent, one of Scottish-Irish descent, and one French family. Multipoint linkage analysis gave a lod score of 5.09 at marker D13S175. The two families of French-Canadian descent share haplotypes with those reported by Kibar et al (1996), indicating a common founder. The French and Scottish-Irish families do not demonstrate the common haplotype, indicating that the mutations in these populations are most likely of different origin.

Autosomal dominant preaxial deficiency, postaxial polydactyly, and hypospadias.

We report on 3 individuals, a man and his son and daughter, who were born with preaxial deficiencies of the hands and feet and postaxial polydactyly of the hands. Both males also had glandular hypospadias. Certain of these findings resemble those found in the hand-foot-genital syndrome; however, we conclude that this family has a hitherto unreported autosomal dominant condition. Production by a single gene defect of preaxial deficiencies and postaxial polydactyly in the same individual is of note.

Did Robert Louis Stevenson have hereditary hemorrhagic telangiectasia?

Chronic illness played a major role in the life and literary success of Robert Louis Stevenson. However, the exact nature of his chronic illness remains unclear. It is possible that Stevenson had hereditary hemorrhagic telangiectasia (Osler-Rendu-Weber Syndrome). This would explain his chronic respiratory complaints, recurrent episodes of pulmonary hemorrhage, and his death, at age 44 years, of probable cerebral hemorrhage. It would also explain his mother's hitherto unreported but apparent stroke, at age 38 years. Further support for this hypothesis might come from new details about the health of Stevenson and his relatives or from molecular analysis of tissue specimens remaining from him.

Genomic medicine: who will practice it? A call to open arms.

The Human Genome Project and other recent developments will broaden and increase the importance of genetics in health care. "Clinical genetics" will become "genomic medicine" and will no longer be almost the sole purview of genetic specialists-medical geneticists, genetic counselors, and genetic advanced practice nurses. The changing use of genetics in health care will require the acquisition of new knowledge, skills, and attitudes by many health care professionals who are not genetic specialists. Such health care professionals will not only be necessary to the widespread integration of genetics into clinical care, but they will make unique contributions to this integration that will add to the quality of genomic medicine. This new use of genetics in health care will also allow, even require, new ways of working for genetic specialists, who will continue to occupy unique and vital roles.

Chromosome 7p--syndrome: craniosynostosis with preservation of region 7p2.

Deletion of a portion of the short arm of chromosome 7 is associated with a recognizable phenotype which often includes craniosynostosis. Recent reports have suggested that craniosynostosis occurs only if there is a deletion involving band 7p21 or the segment distal to that band. We report on a boy who had an interstitial deletion of 7p, not involving band 7p21 or the segment distal to that band, who nevertheless had craniosynostosis. Thus, it appears that the determination of craniosynostosis in this syndrome is more complicated than has been suggested previously.

Possible common pathogenetic mechanisms for Poland sequence and Adams-Oliver syndrome.

We report on 2 families having members affected with the Poland sequence and Adams-Oliver syndrome. In the first family, a 5-month-old boy presented with Adams-Oliver syndrome; his mother had Poland sequence. In the second family, a 12-year-old boy and his mother presented with findings suggestive of Adams-Oliver syndrome and Poland sequence. This suggests that the same genetic predisposition may result in either or both conditions.

Diagnostic criteria for hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome).

Hereditary Hemorrhagic Telangiectasia (HHT) is easily recognized in individuals displaying the classical triad of epistaxis, telangiectasia, and a suitable family history, but the disease is more difficult to diagnosis in many patients. Serious consequences may result if visceral arteriovenous malformations, particularly in the pulmonary circulation, are unrecognized and left untreated. In spite of the identification of two of the disease-causing genes (endoglin and ALK-1), only a clinical diagnosis of HHT can be provided for the majority of individuals. On behalf of the Scientific Advisory Board of the HHT Foundation International, Inc., we present consensus clinical diagnostic criteria. The four criteria (epistaxes, telangiectasia, visceral lesions and an appropriate family history) are carefully delineated. The HHT diagnosis is definite if three criteria are present. A diagnosis of HHT cannot be established in patients with only two criteria, but should be recorded as possible or suspected to maintain a high index of clinical suspicion. If fewer than two criteria are present, HHT is unlikely, although children of affected individuals should be considered at risk in view of age-related penetration in this disorder. These criteria may be refined as molecular diagnostic tests become available in the next few years.

The Human Placenta Project: placental structure, development, and function in real time.

Despite its crucial role in the health of both the fetus and the pregnant woman, the placenta is the least understood human organ. Since a growing body of evidence also underscores the importance of placental development in the lifelong health of both mother and offspring, this lack of knowledge about placental structure and function is particularly concerning. Given modern approaches and technologies and the ability to develop new methods, we propose a coordinated "Human Placenta Project", with the ultimate goal of understanding human placental structure, development, and function in real time.

Human genetics on the web.

Use of the World Wide Web ("the web") and our knowledge of human genetics are both currently expanding rapidly. By allowing swift, universal, and free access to data, the web has already played an important role in human genetics research. It has also begun to change the way that information is shared in clinical genetics and, to a lesser degree, affect how education in human genetics occurs. There are scores of web sites helpful to those interested in either research or clinical aspects of human genetics. The web and related communication technologies should continue to play increasingly important roles in human genetics.

Educating the medical community through a teratology newsletter.

To educate a geographically and professionally diverse group of health care providers about teratology in an economic and efficient manner, we developed a locally written and distributed teratology newsletter. Response to the newsletter, from readers as well as from our staff and funding agencies, suggests that such a newsletter can be a valuable tool in educating medical communities about teratology.

Preconceptional family health evaluation: A regional education program for family planning clients and health professionals.

The Preconceptional Family Health Evaluation Program was a regional project developed and funded for 2 years by the New England Regional Genetics Group (NERGG) to educate family planning health professionals about genetics, and to offer family planning clients preconceptional identification of genetic and environmental exposure risks. To meet these goals, genetic education was provided on a regional basis to 45 family planning professionals. A self-administered family health risk questionnaire adaptable to individual family planning settings was developed. Five hundred and twenty-nine family planning clients voluntarily completed the questionnaire. Cigarette smoking (35%) and alcohol use (57%) were two major categories of risks identified. The Preconceptional Family Health Evaluation Program was well received by all participants and provided an effective means for regional education of family planning health professionals. As a result of the program, state program planners, clinical genetics services, and family planning health professionals developed a strong relationship that will serve future educational and genetic risk screening efforts.

Clinical heterogeneity in hereditary haemorrhagic telangiectasia: are pulmonary arteriovenous malformations more common in families linked to endoglin?

Pulmonary arteriovenous malformations (PAVMs) occur in up to 27% of patients with hereditary haemorrhagic telangiectasia (HHT) and are associated with a rate of paradoxical cerebral embolism at presentation of up to 36%. At least two different loci have been shown for HHT. Mutations in endoglin have been found in some families and the locus designated ORW1. In other families this locus has been excluded. In this paper we confirm that in families linked to ORW1 there is a prevalence of PAVMs among affected members of 29.2%, compared to a prevalence of 2.9% in families in which this locus has been excluded (chi 2 = 19.2, p < 0.001). This information can be used to decide how to screen HHT patients for PAVMs.