Hereditary hemorrhagic telangiectasia. Genetics, pathogenesis, clinical manifestation and management.

Hereditary hemorrhagic telangiectasia HHT, Morbus Osler or Osler-Weber-Rendu syndrome OMIM 187300, is an autosomal dominant disorder characterized by epistaxis, telangiectasia, multi-systemic vascular dysplasia and clinical presentation of wide variation. The pathogenesis involves dilated post-capillary venules or telangiectases in the mucus membrane of various organs as well as larger arteriovenous malformations. Genetic heterogeneity of HHT is confirmed; 2 disease loci, ACVRL1 and ENG genes, have been identified and characterized. The 2 major types of the disease, HHT1 and HHT2, are attributed to mutations in the ENG and ACVRL1 genes. ENG and ACVRL1 genes code for proteins, namely endoglin and activin-receptor-like kinase 1 ALK-1, which are members of the TGF-beta receptor family, are essential for maintaining vascular integrity. Another gene has been implicated in HHT; the HHT3 locus linked to chromosome 5. In the last 2 decades, the genetics, pathogenesis, clinical manifestations and management of HHT have been extensively researched. At this stage, it is deemed appropriate to review the wealth of information accumulated on the topic. Better understanding of the functions of endoglin, ALK-1, and other proteins involved in the pathogenesis of HHT should facilitate better management of patients with this disorder.

Hereditary hemorrhagic telangiectasia is caused by the Q490X mutation of the ACVRL1 gene in a large Arab family: support of homozygous lethality.

In a large Saudi Arabian family with hereditary hemorrhagic telangiectasia (HHT), we identified ACVRL1 (ALK1) nonsense mutation Q490X in 40 HHT patients and three healthy children, but neither in 11 individuals with epistaxis, 41 other healthy family members, nor in 50 healthy unrelated Saudi Arabian controls. Sequence analysis of the entire coding region of the ACVRL1 and ENG genes in five of the 11 epistaxic individuals did not reveal any other disease-causing mutation. Epistaxis seems to be a relatively common phenocopy of HHT in the family under study. One couple, both affected by HHT and carriers of Q490X, had 12 pregnancies. Three of them ended in spontaneous abortion, four in early neonatal death, and only five yielded living offspring, all of which had HHT and were Q490X heterozygous. This observation corroborates previous claims that homozygosity for HHT-causing mutations is lethal.

Increased seroprevalence of human herpes virus-8 in renal transplant recipients in Saudi Arabia.

BACKGROUND: Human herpes virus-8 (HHV-8) is a herpes virus that is always associated with Kaposi's sarcoma. Previous studies suggested a high rate of Kaposi's sarcoma in renal transplant patients in Saudi Arabia. The aim of this study was to investigate the prevalence of HHV-8 in Saudi renal transplant recipients and healthy controls. METHODS: An immunofluorescence technique was used to detect antibodies to the latent nuclear antigen (LANA) of HHV-8 in renal transplant patients, members of a family affected with Kaposi sarcoma, as well as healthy controls. RESULTS: A significantly higher HHV-8 seroprevalence was detected in renal transplant recipients from Saudi Arabia (27 out of 150; 18%) and in members of a family affected with Kaposi sarcoma (seven out of 10; 70%) relative to the seroprevalence in healthy controls (10 out of 577; 1.7%). Seropositivity for HHV-8 in these transplant patients was not significantly influenced by: the existence of relatives with kidney failure, the donors' country of origin, the recipients' home region within Saudi Arabia, the haemodialysis centre, the time that elapsed since the renal transplantation operation and the immunosuppressive regimen used. CONCLUSION: The present results provide some explanation for the previously noted high incidence of Kaposi's sarcoma in Saudi transplant patients.

Hepatic manifestation is associated with ALK1 in hereditary hemorrhagic telangiectasia: identification of five novel ALK1 and one novel ENG mutations.

Hereditary hemorrhagic telangiectasia (HHT), or Osler-Rendu-Weber syndrome, is a heterogeneous inherited disorder characterized by multi-systemic vascular dysplasia and wide variation in its phenotypic expression. Hepatic manifestation is seen in about 8 to 30 % of the patients. The molecular basis for liver involvement is unknown. We screened the two known HHT disease loci, the ALK1 (ACVRL1) and ENG genes, for mutations in a clinically well-characterized group of HHT patients with or without liver involvement. Mutations in the ALK1 gene were detected in eight out of 10 HHT patients with hepatic manifestation. Among nine HHT patients without liver involvement, four had mutations in the ALK1, and three in the ENG genes, respectively. In one patient with hepatic manifestation a mutation was detected in both the ALK1 and ENG genes. No mutation could be detected in two patients with liver involvement and, likewise, in two patients without hepatic manifestation. In this study, we have identified five novel ALK1 and one ENG disease-causing mutations. We conclude that hepatic manifestation in HHT patients is associated with mutations in the ALK1 gene, but rarely with ENG mutations.

Naxos disease in an Arab family is not caused by the Pk2157del2 mutation. Evidence for exclusion of the plakoglobin gene.

OBJECTIVE: Naxos disease is a rare hereditary disorder characterized by palmoplantar keratoderma, woolly hair and cardiomyopathy. This study aims to determine whether Naxos disease in a Saudi Arab family is caused by the Pk2157del2 mutation that was identified in Greek families from Naxos Island where the disease had originally been described. METHODS: This study was undertaken at King Fahad Hospital of the University, Al-Khobar, and the Medical University of Hannover, in the spring of 2003. Naxos disease has been encountered in a 2-year-old girl and her 30-year-old aunt of a Saudi Arab family. Deoxyribonucleic acid samples of this family were analyzed by polymerase chain-reaction (PCR) amplification of the respective region of the plakoglobin gene, and direct nucleotide sequencing of the PCR-products. Segregation analysis was performed employing the newly detected IVS11+22G/A polymorphism. RESULTS: Molecular genetic analysis of the DNA sample of the child diagnosed with Naxos disease showed absence of the Pk2157del2 mutation. In addition, the segregation analysis revealed heterozygosity for IVS11+22G/A in the affected girl. CONCLUSION: Absence of the Pk2157del2 frameshift in the affected child proved that Naxos disease in this Saudi Arab family is not caused by the same mutation that was identified in the Greek families. Furthermore, heterozygosity for the IVS11+22G/A polymorphism provided evidence for exclusion of the plakoglobin gene in this consanguineous family.

The cytokine TNF-alpha. Genetics and suitability for prenatal risks assessment.

The tumor necrosis factor (TNF-alpha) is a cytokine known as a mediator of inflammation and immunity. The genes coding the tumor necrosis factors alpha and beta are considered part of class III major histocompatability complex. The 2 involved genes have been mapped to chromosome 6. Certain mutations in the TNF-alpha gene are believed to be causative for increased production of the cytokine. In this respect, the most common variant is the TNF2 allele, a single nucleotide substitution of guanine by adenine at position -308 relative to the promoter transcription site of the gene. Elevated production of TNF-alpha has been found to be associated with several infectious diseases including malaria. Elevated levels of TNF-alpha have also been observed to associate with increased risk of preterm delivery, chorioamnionitis and fetal morbidity including encephalopathy. The present article reviews the genetics of the cytokine TNF-alpha and discusses its suitability as a candidate marker for assessment of increased risk of preterm delivery and fetal morbidity.

Pre-eclampsia: maternal risk factors and perinatal outcome.

OBJECTIVE: The aim of this study was to throw light on the incidence of pre-eclampsia (PE) in women attending for care and delivery at a hospital in Saudi Arabia, and analyze the maternal risk factors and outcome of mothers and neonates in pregnancies complicated by PE. METHODS: This retrospective study involved almost all women (n = 27,787) who delivered at King Fahad Hospital of the University in a 10-year period (1992-2001). The maternal records were reviewed for age, parity, gestational age, mode of delivery, antenatal care, onset of PE, severity of proteinuria, and the frequency of antenatal and intrapartum complications. The neonatal records were reviewed for perinatal outcome including birth weight, frequency of stillbirths, and neonatal deaths. RESULTS: Among the study cohort of pregnancies, 685 women, i.e. 2.47%, were diagnosed as having PE among whom a high proportion (42.0%) were nulliparous women. Similarly, PE was encountered at a high percentage (40.0%) in women at the extreme of their reproductive age (< 20 and >40 years), and more women with PE delivered prematurely (30.2%) as compared to healthy controls (13.5%). Spontaneous vaginal deliveries were less frequent in women with PE (69.2%) as compared with healthy controls (86.2%). Instrumental deliveries, with spontaneous labor, amounted to 15.9% in women with PE, but they comprised only 2.9% in healthy women. The deliveries were more likely to be induced (22.8%) or be performed by cesarean section (14.9%) in women with PE than in healthy controls (6.8% and 9.6%). Placental abruption was the most common maternal complication (12.6%) in women with PE, followed by oligouria (7.9%), coagulopathy (6.0%), and renal failure (4.1%). The perinatal outcome of pregnancies with PE shows that stillbirths (2.34%) and early neonatal deaths (1.02%) comprised an overall mortality rate of 33.6 per 1,000. More stillbirths and neonatal deaths showed a tendency to be associated with the severe form of PE (diastolic BP > or =120), as compared with the mild form (diastolic BP 90-110). Stillbirths and neonatal deaths appear to be associated with women who had no or irregular antenatal care and whose proteinuria amounted to or exceeded 3 g per 24 h, when delivery occurred at 28th gestational week or less, and when the birth-weight of the neonates was between 500 and 1,000 g. CONCLUSION: We document a hospital-based incidence rate of PE of 2.47%, with a high proportion of PE cases occurring among nulliparous women and those at the extreme ends of the reproductive age. More maternal and neonatal complications were encountered in women with PE when the PE was severe, when the pregnancy had to be terminated early, when there was no regular antenatal care, the birth-weight was low, or the proteinuria was severe.

BRCA1 and BRCA2 mutations in breast cancer patients from Saudi Arabia.

OBJECTIVE: The aim of this pilot study was to screen the major segments of the BRCA1 and BRCA2 genes for disease-associated mutations in Arab and Asian women with breast cancer from the Kingdom of Saudi Arabia. METHODS: Deoxyribonucleic acid samples from 29 Arab women and 11 Asian women, with unilateral breast cancer were investigated for BRCA1 and BRCA2 mutations. For this purpose single strand conformation polymorphism and direct nucleotide sequencing techniques were employed. This study was carried out at King Fahad Hospital of the University, Al-Khobar, Kingdom of Saudi Arabia, during the time frame March 2000 through to August 2001. RESULTS: One novel BRCA2 truncating mutation, the frame-shift mutation 2482delGACT, was uncovered in an Arab patient of Palestinian descent. This mutation is a 4-nucleotide deletion that creates a stop signal at codon 770 of the BRCA2 transcript. The BRCA1 disease-associated mutation Arg841Trp was detected in another Arab patient from Egypt. The clinical presentation in the 2 heterozygous carriers of these 2 mutations is described here. In addition the unclassified BRCA1 variant Phe486Leu combined with Asn550His, and the unclassified BRCA2 variant Asp1420Tyr, were identified in Arab patients. Five BRCA1 polymorphisms and 6 BRCA2 polymorphisms were detected at different allele frequencies in both mutation carriers and patients with normal genotype. CONCLUSION: We conclude that BRCA1 and BRCA2 mutations are likely to contribute to the pathogenesis of familial breast cancer in female patients from the Kingdom of Saudi Arabia.

PCR-based analysis of cystic fibrosis mutations specific for Saudi patients.

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Experimental cutaneous leishmaniasis. IV. The humoral response of Cebus apella (Primates: Cebidae) to infections of Leishmania (Leishmania) amazonensis, L. (Viannia) lainsoni and L. (V.) braziliensis using the direct agglutination test.

The direct agglutination test (DAT) was used to evaluate the serological response of 150 serum samples taken from 15 captive-bred capuchin monkeys Cebus apella. These animals had been experimentally infected with either L. (Leishmania) amazonensis, L. (Viannia) lainsoni or L. (V.) braziliensis. Monkeys infected with L. (L.) amazonensis or L. (V.) lainsoni were challenged with the homologous parasite one month after their spontaneous cure. DAT antigens were prepared from L. (L.) donovani, L. (L.) amazonensis and L. (V.) braziliensis. Antigens were difficult to standardise and it was impossible to produce an L. (V.) lainsoni antigen as parasites remained aggregated even after trypsinization. The DAT detected significant humoral responses in all the infected monkeys. Titres were higher when homologous antigens were used, especially in secondary responses. This suggests that homologous antigen should be used to detect antibodies in human cutaneous leishmaniasis.

Reactivity of various leishmanial antigens in a direct agglutination test and their value in differentiating post-kala azar dermal leishmaniasis from leprosy and other skin conditions.

A direct agglutination test (DAT) for the detection of post-kala azar dermal leishmaniasis (PKDL) was evaluated in conditions that simulate the disease clinically or immunologically. A reference strain of Leishmania donovani (LEM 1399), and antigen preparations from Leishmania isolates from Bangladeshi patients with post-kala azar dermal leishmaniasis or visceral leishmaniasis were used. A titre of at least 51,200 was obtained in tests of patients with PKDL with all three antigens, whereas a maximum titre of 1600 was recorded in patients with cutaneous leishmaniasis, mucocutaneous leishmaniasis or leprosy. Antigens from dermal isolates of L. tropica (LV 140) and L. braziliensis (LV 65) yielded titres of 1600-6400 in patients with PKDL. The lowest titre recorded in 70 patients tested with the homologous PKDL antigen was 409,600. In patients with leprosy, cutaneous leishmaniasis, syphilis, onchocerciasis, tuberculosis, blastomycosis or vitiligo, titres ranged from 100 to 1600. Tha DAT is better than current parasitological and histopathological methods for the diagnosis of PKDL in areas in which leprosy is co-endemic.

Evaluation of cleaving agents other than trypsin in direct agglutination test for further improving diagnosis of visceral leishmaniasis.

Trypsin treatment of Leishmania promastigote antigen has proved to be indispensible in the direct agglutination test (DAT) for the diagnosis of visceral leishmaniasis (VL) and canine visceral leishmaniasis (CVL). In the present study four antigen batches were prepared with pronase (400 micrograms/ml), lipase (0.45% [wt/vol]), pancreatin (0.3% [wt/vol]), or 2-mercaptoethanol (2-ME) (1.2% [vol/vol]) at a ratio of 20:1 versus promastigote packed cell volume or a density of 10(8)/ml. Batches prepared in this way performed satisfactorily when compared with the performance of the initial trypsinated antigen. Even higher was the sensitivity and specificity of the 2-ME-processed antigen, scoring a minimum DAT titer of 1:102,400 in the VL and CVL group and a maximum of 1:400 in the negative control group. Corresponding titers ranging from 1:6,400 to 1:12,800 and 1:800 to 1:1,600 were obtained with the antigen variants processed with pronase, lipase, pancreatin, or trypsin. By combining the use of indigenous Leishmania donovani subspecies from Sudan, Bangladesh, or Morocco and incorporating 2-ME instead of trypsin in the antigen processing step, a threefold increase in titer was attained in sera from the respective areas where VL is endemic. 2-ME-processed antigen suspensions maintained stability at 4 degrees C for up to 9 months, as evidenced by the absence of autoagglutination and the reproducibility of DAT readings with standard sera. The specificity of DAT was further improved by supplementation of the sample diluent with 0.03 M urea and incubation of the test plates at 37 degrees C for 1 h. Titers ranging from 1:200 to 1:12,800 in the sera of patients and laboratory animals infected with various trypanosoma species were significantly reduce (/=1:51,200) against 2-ME-processed antigen, despite the incorporation of urea into the DAT.

Visceral leishmaniasis in Bangladesh: the value of DAT as a diagnostic tool.

The direct agglutination test (DAT) was performed on 480 serum samples from suspected cases of visceral leishmaniasis (VL) in different parts of Bangladesh. Significant titres (> or = 1:3200) were found in 257 sera (53.5%). All patients with positive bone-marrow aspirates also had significant DAT titres. The male:female seroprevalence ratio was 2:1 and the age-group 0-20 years was the most affected. The DAT proved a simple, economical and reliable diagnostic test for VL.

Evora district as a new focus for canine leishmaniasis in Portugal.

On the basis of information acquired from local health authorities in Evora district of Portugal on cases of visceral leishmaniasis (VL), an epidemiology survey study was conducted. To determine the prevalence of anti-Leishmania antibodies in the local human and canine populations residing in Evora town and 14 adjacent villages, blood samples collected from 885 children and 3,614 dogs were tested in a direct agglutination test (DAT). Seropositivity for Leishmania parasite obtained by DAT in both endemic populations was further confirmed by an enzyme-linked immunosorbent assay (ELISA) and immunofluorescence test (IFAT). For identification of the responsible sandfly vector, 79 biotopes within the study areas were surveyed. In the infantile population assessed, none of the children screened showed an antibody level indicative (titer, > = 1:3200) of visceral leishmaniasis in the DAT. However, agglutinating antibody rates ranging from 0.7% to 6.9% were obtained in dogs residing in Evora and 11 adjacent villages. Concordant seropositivity of 94.04% was obtained by ELISA and IFAT in the same canine population (141) identified by DAT. Of the 159 sandflies captured, 67 were identified as Phlebotomus sergenti; 15, as P. ariasi; 58, as P. perniciosus; and 19, as Sergentomyia minuta. Unlike the results previously reported in Alto-Douro and Algarve districts of Portugal, as compared with the other three species, P. sergenti appears to be more abundant in Evora district.(ABSTRACT TRUNCATED AT 250 WORDS)

Applicability of direct agglutination test (DAT) at a rural health setting in Bangladesh and feasibility of local antigen production.

As part of a large-scale sero-epidemiological survey on visceral leishmaniasis (VL) carried out in Mymensingh district of Bangladesh, applicability of DAT was assessed at the level of a rural health setting in Trishal (upazila) subdistrict. Despite the relatively less optimal conditions encountered, 5854 inhabitants from 7 villages appendant to Trishal were assessed for VL. The demographic distribution for sero-positivity obtained at the rural setting was comparable to that found by DAT as executed at the central laboratory (IEDC&R, Dhaka) on 9619 inhabitants from the same upazila. The overall sero-prevalence rate was 4.4% compared to 3.7% obtained in the population assessed at the central laboratory. In either study, similar VL prevalence rates of 2.1% were obtained in the male populations. Irrespective of sex, younger population (< 20 years) in both studies appeared to have higher VL incidence rate (2.3% and 2.6%) than others of 21- > or = 90 years (1.4% and 1.8%). Local production of DAT antigen employing an authochtonus L. donovani isolate was attempted at the central laboratory (IEDC&R) in Dhaka. By comparison with the reference antigen, titres obtained in all 33 VL sera tested were equally higher (1:6400- > or =: 51200) than in 35 out of 38 negative controls (< or = 1:400-1:1600). A comparable level of reactivity was also obtained in 53 VL and 52 negative control sera using a well characterized L. donovani strain (MHOM/IN/80/D88) from India. However, unlike the reference strain, titres obtained in 7 endemic controls were significantly higher with the authochtonous and homologous antigen (1:3200 - 1:6400) than with the reference (1:100 - 1:1600). The results signify the advantage of employing indigenous L. donovani isolates to further improve DAT sensitivity for detection of early and sub-clinical VL.

Prevalence of agglutinating anti-Leishmania antibodies in two multi-thousand Bengoli communities.

Control of endemic visceral leishmaniasis (VL) in large communities requires a feasible epidemiological indicator capable of monitoring on-going transmission rather than mere exposure to the parasite. Following confirmation of the desired level of reliability for laboratory diagnosis of VL, the direct agglutination test (DAT) was employed to estimate VL sero-prevalence in the endemic upazilas (subdistricts) of Trishal and Shahjadpur within Mymensingh and Sirajganj districts of Bangladesh. DAT antigen production was duly increased to allow coverage of a study population of 17826 inhabitants, 9619 of whom resided in Trishal, 7328 in Shahjadpur and 879 in Teknaf (Cox's Bazar), a known Leishmania-free district in Bangladesh. Despite large-scale production in batches of 1120-4000 ml (each sufficient for 1176-6400 screening doses), all DAT antigen batches performed as required in quality control tests for sensitivity, specificity and stability. It was convenient for both collection and testing to take the required samples of whole blood by finger prick. A cross-sectional survey revealed VL point prevalences of 4.40% in Trishal and 6.75% in Shahjadpur, compared with an extremely low rate of 0.34% in non-endemic Teknaf. In both endemic upazilas (Trishal and Shahjadpur) VL was more prevalent (2.56-4.5%) in persons up to 20 years of age than in those 21 years of age and older (1.84-2.25%). Of 918 subjects recorded as seropositives, 539 were VL-asymptomatic and 379 were VL-symptomatic with various degrees of suspicion. Diagnosis of VL was established in 125 symptomatic seropositives subjects, either by demonstrating the presence of Leishmania amastigotes (29), or by positive DAT results combined with presentation of typical VL signs (96).(ABSTRACT TRUNCATED AT 250 WORDS)

[Canine leishmaniasis in the region of Enfidha (Central Tunisia). Assessment of seroprevalence with direct agglutination (DAT) and indirect immunofluorescence (IFAT)]. / La leishmaniose canine dans la région d'Enfidha (Tunisie centrale). Estimation de la séro-prévalence par agglutination directe (DAT) et immunofluorescence indirecte (IFAT).

In order to assess canine leishmaniasis prevalence rate in Enfidha area, considered to be the most important kala-azar focus in Sousse Governorate, a serological survey was carried out in 6 localities. 265 sera were examined by DAT and IFAT. 16 (6.03%) showed positive results for anti-leishmania antibodies with significant variations according to the locality. A fairly DAT-IFAT good correlation was observed.

Positive response to sodium antimony gluconate administration in visceral leishmaniasis seropositive patients.

In a prospective study conducted in Mymensingh district of Bangladesh, 1, 273 patients were assessed for the presence of visceral leishmaniasis (VL). Sodium antimony gluconate (SAG) was successfully administered to 715 patients with parasitologically confirmed infection. In the remaining 558, although there was clinical indication of VL, Leishmania donovani parasites could not be demonstrated. Administration of SAG in this group was on the grounds of the prevailing symptoms, exclusion of malaria and a positive direct agglutination test (DAT). Significant improvements in the clinical and hematological parameters were observed in 547 (98%) of the unconfirmed VL cases. On the basis of the parasitological findings or positive response to specific anti-Leishmania chemotherapy, the sensitivity and specificity of the DAT were 99.6% and 97.7% respectively. The results supported the reliability of DAT for diagnosis of VL at levels below that of parasitological detection.

A killing disease epidemic among displaced Sudanese population identified as visceral leishmaniasis.

A fatal disease epidemic affected the Bentiu area in southern Sudan and led to a mass migration of the Nuer tribe searching for treatment. The initially available information revealed a high mortality rate due to a possible occurrence of tuberculosis, malaria, enteric fever or visceral leishmaniasis (VL). Serological screening of 53 of the most severely affected patients in an enzyme-linked immunosorbent assay (ELISA) or an improved direct agglutination test (DAT) revealed positivity for VL. In 39 of those patients, diagnosis was confirmed by identification of Leishmania donovani amastigotes in lymph node or bone-marrow aspirates. In a total of 2714 patients observed, 1195 (44.0%) had clinical symptoms suggesting VL: DAT positive titers (1:3200-greater than or equal to 1:12800) were obtained in 654 (24.1%), of whom 325 were confirmed parasitologically. Forty-two VL cases died before or during treatment, giving a mortality rate of 6.4%. Among the intercurrent infections diagnosed in the VL population (654), respiratory involvements (31.7%) and malaria (10.7%) were most prevalent. With the exception of four (0.6%), all other VL patients (509) responded readily to sodium stibogluconate. The factors initiating the outbreak are discussed. Malnutrition and nomadic movements to potential VL endemic areas appeared to be the most important. HIV infection as a possible predisposition seemed remote considering the clinical and epidemiological similarity to VL occurring in East Africa, adequate humoral response in DAT, and immediate positive response to specific anti-Leishmania chemotherapy.