Primary pulmonary hypertension is associated with reduced pulmonary vascular expression of type II bone morphogenetic protein receptor

BACKGROUND: Mutations in the type II receptor for bone morphogenetic protein (BMPR-II), a receptor member of the transforming growth factor-beta (TGF-beta) superfamily, underlie many familial and sporadic cases of primary pulmonary hypertension (PPH). METHODS AND RESULTS: Because the sites of expression of BMPR-II in the normal and hypertensive lung are unknown, we studied the cellular localization of BMPR-II and the related type I and II receptors for TGF-beta by immunohistochemistry in lung sections from patients undergoing heart-lung transplantation for PPH (n=11, including 3 familial cases) or secondary pulmonary hypertension (n=6) and from unused donor lungs (n=4). In situ hybridization was performed for BMPR-II mRNA. Patients were screened for the presence of mutations in BMPR2. In normal lungs, BMPR-II expression was prominent on vascular endothelium, with minimal expression in airway and arterial smooth muscle. In pulmonary hypertension cases, the intensity of BMPR-II immunostaining varied between lesions but involved endothelial and myofibroblast components. Image analysis confirmed that expression of BMPR-II was markedly reduced in the peripheral lung of PPH patients, especially in those harboring heterozygous BMPR2 mutations. A less marked reduction was also observed in patients with secondary pulmonary hypertension. In contrast, there was no difference in level of staining for TGF-betaRII or the endothelial marker CD31. CONCLUSIONS: The cellular localization of BMPR-II is consistent with a role in the formation of pulmonary vascular lesions in PPH, and reduced BMPR-II expression may contribute to the process of vascular obliteration in severe pulmonary hypertension

A novel PCFT gene mutation (p.Cys66LeufsX99) causing hereditary folate malabsorption

Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder which is characterized by impaired intestinal folate malabsorption and impaired folate transport into the central nervous system. Mutations in the intestinal folate transporter PCFT have been reported previously in only 10 individuals with this disorder. The purpose of the current study was to describe the clinical phenotype and determine the molecular basis for this disorder in a family with four affected individuals. A consanguineous family of Pakistani origin with autosomal recessive HFM was ascertained and clinically phenotyped. After genetic linkage studies all coding exons of the PCFT gene were screened for mutations by direct sequencing. The clinical phenotype of four affected patients is described. Direct sequencing of PCFT revealed a novel homozygous frameshift mutation (c.194dupG) at a mononucleotide repeat in exon 1 predicted to result in a truncated protein (p.Cys66LeufsX99). This report extends current knowledge on the phenotypic manifestations of HFM and the PCFT mutation spectrum

Familial Infiltrative Fibromatosis (Desmoid Tumours) (MIM135290) Caused by a Recurrent 3′ APC Gene Mutation

Desmoid tumours are generally very rare but occur about 100 times more frequently in the colorectal cancer predisposition syndrome familial adenomatous polyposis (MIM 175100), being represented in about 10% of patients. In addition to desmoid disease occurring in familial adenomatous polyposis (FAP) there exist familial infiltrative fibromatosis (MIM 135290) kindreds where there is no evidence of FAP. Previously we have described a kindred with familial infiltrative fibromatosis (FIF) in which desmoid tumours were associated with nonpolyposis colorectal cancer. FAP is caused by mutations in the APC gene and various genotype-phenotype relationships have been defined including reports that colorectal polyposis is less severe with mutations 5′ to codon 157 and that the risk of desmoid tumours is high in FAP patients with APC gene mutations between codons 1444 and 1598. There is relatively little information on the phenotype of APC gene mutations 3′ to codon 1598; however, one large family has been reported with a mutation at codon 1987 which presents with a highly variable phenotype which includes desmoid disease. We screened our original FIF kindred and three further families with a similar phenotype for mutations in the APC gene. A 4 bp frameshift deletion in codon 1962 was identified in the original FIF kindred and two further apparently unrelated families. Haplotype analysis suggests a common origin for the APC mutation in all three families. Affected individuals had no evidence of congenital hypertrophy of the retinal pigment epithelium. Colorectal polyposis was variable, and most affected patients had either none or a few late onset polyps. These findings demonstrate (i) that FAP and FIF are allelic, and (ii) that APC gene mutations which truncate the APC protein distal to the beta-catenin binding domain are associated with desmoid tumours, absent CHRPE and variable but attenuated polyposis expressio

Initiation codon mutation in βB1-crystallin (CRYBB1) associated with autosomal recessive nuclear pulverulent cataract

PurposeTo identify the molecular basis for autosomal recessively inherited congenital non-syndromic pulverulent cataracts in a consanguineous family with four affected children.MethodsAn autozygosity mapping strategy using high density SNP microarrays and microsatellite markers was employed to detect regions of homozygosity. Subsequently good candidate genes were screened for mutations by direct sequencing.ResultsThe SNP microarray data demonstrated a 24.96 Mb region of homozygosity at 22q11.21-22q13.2 which was confirmed by microsatellite marker analysis. The candidate target region contained the beta-crystallin gene cluster and direct sequencing in affected family members revealed a novel mutation in CRYBB1 (c.2T>A; p.Met1Lys).ConclusionsTo our knowledge this is the first case of an initiation codon mutation in a human crystallin gene, and only the second report of a CRYBB1 mutation associated with autosomal recessive congenital cataracts. In addition, although a number of genetic causes of autosomal dominant pulverulent cataracts have been identified (including CRYBB1) this is the first gene to have been implicated in autosomal recessive nuclear pulverulent cataract

Impaired natural killer cell phenotype and function in idiopathic and heritable pulmonary arterial hypertension

BACKGROUND: Beyond their role as innate immune effectors, natural killer (NK) cells are emerging as important regulators of angiogenesis and vascular remodeling. Pulmonary arterial hypertension (PAH) is characterized by severe pulmonary vascular remodeling and has long been associated with immune dysfunction. Despite this association, a role for NK cells in disease pathology has not yet been described. METHODS AND RESULTS: Analysis of whole blood lymphocytes and isolated NK cells from PAH patients revealed an expansion of the functionally defective CD56(-)/CD16(+) NK subset that was not observed in patients with chronic thromboembolic pulmonary hypertension. NK cells from PAH patients also displayed decreased levels of the activating receptor NKp46 and the killer immunoglobulin-like receptors 2DL1/S1 and 3DL1, reduced secretion of the cytokine macrophage inflammatory protein-1β, and a significant impairment in cytolytic function associated with decreased killer immunoglobulin-like receptor 3DL1 expression. Genotyping patients (n=222) and controls (n=191) for killer immunoglobulin-like receptor gene polymorphisms did not explain these observations. Rather, we show that NK cells from PAH patients exhibit increased responsiveness to transforming growth factor-β, which specifically downregulates disease-associated killer immunoglobulin-like receptors. NK cell number and cytotoxicity were similarly decreased in the monocrotaline rat and chronic hypoxia mouse models of PAH, accompanied by reduced production of interferon-γ in NK cells from hypoxic mice. NK cells from PAH patients also produced elevated quantities of matrix metalloproteinase 9, consistent with a capacity to influence vascular remodeling. CONCLUSIONS: Our work is the first to identify an impairment of NK cells in PAH and suggests a novel and substantive role for innate immunity in the pathobiology of this disease

Clinical and molecular genetic features of pulmonary hypertension in patients with hereditary hemorrhagic telangiectasia

BACKGROUND: Most patients with familial primary pulmonary hypertension have defects in the gene for bone morphogenetic protein receptor II (BMPR2), a member of the transforming growth factor beta (TGF-beta) superfamily of receptors. Because patients with hereditary hemorrhagic telangiectasia may have lung disease that is indistinguishable from primary pulmonary hypertension, we investigated the genetic basis of lung disease in these patients. METHODS: We evaluated members of five kindreds plus one individual patient with hereditary hemorrhagic telangiectasia and identified 10 cases of pulmonary hypertension. In the two largest families, we used microsatellite markers to test for linkage to genes encoding TGF-beta-receptor proteins, including endoglin and activin-receptor-like kinase 1 (ALK1), and BMPR2. In subjects with hereditary hemorrhagic telangiectasia and pulmonary hypertension, we also scanned ALK1 and BMPR2 for mutations. RESULTS: We identified suggestive linkage of pulmonary hypertension with hereditary hemorrhagic telangiectasia on chromosome 12q13, a region that includes ALK1. We identified amino acid changes in activin-receptor-like kinase 1 that were inherited in subjects who had a disorder with clinical and histologic features indistinguishable from those of primary pulmonary hypertension. Immunohistochemical analysis in four subjects and one control showed pulmonary vascular endothelial expression of activin-receptor-like kinase 1 in normal and diseased pulmonary arteries. CONCLUSIONS: Pulmonary hypertension in association with hereditary hemorrhagic telangiectasia can involve mutations in ALK1. These mutations are associated with diverse effects, including the vascular dilatation characteristic of hereditary hemorrhagic telangiectasia and the occlusion of small pulmonary arteries that is typical of primary pulmonary hypertension

A combination of mutations in AKR1D1 and SKIV2L in a family with severe infantile liver disease.

Infantile cholestatic diseases can be caused by mutations in a number of genes involved in different hepatocyte molecular pathways. Whilst some of the essential pathways have a well understood function, such as bile biosynthesis and transport, the role of the others is not known. Here we report the findings of a clinical, biochemical and molecular study of a family with three patients affected with a severe infantile cholestatic disease. A novel homozygous frameshift germline mutation (c.587delG) in the AKR1D1 gene; which encodes the enzyme Δ 4-3-oxosteroid 5β-reductase that is required for synthesis of primary bile acids and is crucial for establishment of normal bile flow, was found in all 3 patients. Although the initial bile acid analysis was inconclusive, subsequent testing confirmed the diagnosis of a bile acid biogenesis disorder. An additional novel homozygous frameshift mutation (c.3391delC) was detected in SKIV2L in one of the patients. SKIV2L encodes a homologue of a yeast ski2 protein proposed to be involved in RNA processing and mutations in SKIV2L were recently described in patients with Tricohepatoenteric syndrome (THES). A combination of autozygosity mapping and whole-exome-sequencing allowed the identification of causal mutations in this family with a complex liver phenotype. Although the initial 2 affected cousins died in the first year of life, accurate diagnosis and management of the youngest patient led to successful treatment of the liver disease and disease-free survival.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus.

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability

Inhibition of Overactive Transforming Growth Factor–β Signaling by Prostacyclin Analogs in Pulmonary Arterial Hypertension

YesHeterozygous loss of function mutations in the type II bone morphogenetic protein receptor (BMPR-II), a member of the transforming growth factor (TGF-β) receptor family, underlie the majority of familial cases of pulmonary arterial hypertension (PAH). The TGF-β1 pathway is activated in PAH and inhibitors of TGF-β1 signaling prevent the development and progression of PAH in experimental models. However, the effect of currently utilized therapies on the TGF-β pathway is not known. Prostacyclin analogues remain the first line of treatment for clinical PAH. We hypothesized that these agents effectively decrease the activity of the TGF-β1 pathway. Beraprost sodium (BPS), a prostacyclin analogue selectively inhibits proliferation in a dose-dependent manner in mouse primary pulmonary arterial smooth muscle cells (PASMCs) harbouring a pathogenic BMPR2 nonsense mutation in both the presence and absence of TGF-β1 stimulation. This study demonstrates that this agent inhibits TGF-β1–induced SMAD-dependent and -independent signaling via a PKA dependent pathway by reducing the phosphorylation of SMADs 2 and 3 and p38MAPK proteins. Finally, in a monocrotaline (MCT)-induced rat model of PAH, which is associated with increased TGF-β signaling, this study confirms that treprostinil (TPS), a stable prostacyclin analogue, inhibits the TGF-β pathway by reducing SMAD3 phosphorylation. Taken together, these data suggest that prostacyclin analogues inhibit dysregulated TGF-β signaling in vitro and in vivo and reduce BMPR-II-mediated proliferation defects in mutant mice PASMCs.The authors acknowledge financial support from the British Heart Foundation, United Kingdom (Programme Grant 1-2004-357 to R.C.T. and N.W.M.), a Heptagon Life Science Proof of Concept Fund (grants KCL24 and KCL25 to M.T.N. and R.C.T., respectively), and the Great Britain Sasakawa Foundation (grant B70 to M.T.N.

Mutations in GATA2 cause primary lymphedema associated with a predisposition to acute myeloid leukemia (Emberger syndrome).

We report an allelic series of eight mutations in GATA2 underlying Emberger syndrome, an autosomal dominant primary lymphedema associated with a predisposition to acute myeloid leukemia. GATA2 is a transcription factor that plays an essential role in gene regulation during vascular development and hematopoietic differentiation. Our findings indicate that haploinsufficiency of GATA2 underlies primary lymphedema and predisposes to acute myeloid leukemia in this syndrome