Schistosomal hepatic fibrosis and the interferon gamma receptor: a linkage analysis using single-nucleotide polymorphic markers

A minority of individuals infected with the parasite Schistosoma mansoni develops hepatic fibrosis. HLA studies in Egypt and a candidate gene search in a Sudanese population indicate that the host's genetics contribute to disease susceptibility. In an Egyptian community, 32.7% of individuals 11 years and older had significant fibrosis by WHO ultrasound criteria. Linkage to 10 candidate genes was tested using 89 affected sibling pairs from 40 pedigrees in this community. The candidates included genes that initiate fibrosis, participate in collagen synthesis, or control collagen degradation. Two to four single-nucleotide polymorphisms (SNPs) were genotyped per locus, and 188 individuals were genotyped at 48 markers. Model-free modified Haseman-Elston analysis identified linkage to a SNP in the interferon gamma receptor locus (P=0.000001). There was also weak evidence for linkage to the interleukin 13-4 region and tissue growth factor beta 1.

Measuring morbidity in schistosomiasis mansoni: relationship between image pattern, portal vein diameter and portal branch thickness in large-scale surveys using new WHO coding guidelines for ultrasound in schistosomiasis

OBJECTIVE

World Health Organization consensus meetings on 'Ultrasound in Schistosomiasis' in 1996 and 1997 anticipated further challenges in the global implementation of a standardized protocol for morbidity assessment in schistosomiasis mansoni. We evaluated the performance of the qualitative and quantitative components of the new Niamey criteria.

METHOD

Use of the Niamey protocol among 3954 subjects in two linked, cross-sectional ultrasound surveys of Schistosoma mansoni-endemic populations in Egypt and Kenya.

RESULTS

There were significant differences between Egyptian and Kenyan sites in prevalence and age distribution of S. mansoni-related hepatic fibrosis (36%vs. 3%, P < 0.001). Protocol image pattern scoring could be performed quickly and was stable to interobserver variation. However, there were unintended but systematic differences between study sites in the measurement of portal vein diameter (PVD) and wall thickness. By Niamey criteria, a high prevalence of portal dilation was scored for normal Egyptian subjects, which reduced the predictive value of image pattern for portal hypertension. Using alternative height-indexing of PVD, image pattern plus PVD findings predicted 15% of Egyptians and 2.5% of Kenyans were at risk for variceal bleeding, whereas locally derived PVD norms estimated 25% of Egyptians and 12% of Kenyans to be at possible risk.

CONCLUSION

Niamey scoring criteria performed acceptably as a relative grading system for disease in schistosomiasis mansoni, but failed to account fully for site-to-site variation in test performance and morbidity prevalence. Consequently, standardized image pattern scoring appears to provide the most useful tool for detection and comparison of S. mansoni-associated morbidity in large-scale surveys.

Population-based differences in Schistosoma mansoni- and hepatitis C-induced disease

Two populations with differing histories of Schistosoma mansoni and hepatitis C infection were compared directly for severity of disease and extent of comorbidity. Demographic, parasitologic, and ultrasound surveys were conducted on 2038 Egyptians and on 2120 Kenyans. Hepatitis B and C serologies and transaminase levels were obtained from a subset at each site. Despite significantly lower prevalence and intensity of infection, Egyptians had a higher prevalence of severe schistosomal fibrosis than Kenyans (36.8% vs. 4.6%). Hepatitis C infection was 3 times more prevalent among Egyptians, and evidence of hepatocellular damage was significantly greater among Egyptians. There was no interaction between S. mansoni infection or disease and the prevalence or severity of hepatitis C. For both infections, the intensity or prevalence of infection was a poor predictor of morbidity. The prevalence of disease in the Egyptian population from different pathogens suggests a generalized susceptibility to inflammatory liver disease.

Genetic studies in varicocele infertility. II: Dermatoglyphic pattern

The prime concern of the present work was the analysis of dermatoglyphic patterns in infertile patients presenting with clinically detectable varicocele. In a controlled study conducted on 30 patients and utilizing a slight modification of the original ink method of Cummins and Midlo, the dermatoglyphics on terminal phalanges of the thumb in both hands showed significantly higher incidence of the whorl pattern. Likewise, the index finger in both hands exhibited higher incidence of both the whorl and double loop patterns. Other patterns on the fingers, the plamar creases, axial triradii, hypothenar and thenar eminences, and angle and total ridge count did not alter significantly. Such characteristic dermatoglyphic patterns in varicocele infertile men may furnish additional evidence in support of a genetic cause for varicocelogenesis and its associated gonadal dysfunction. Furthermore, it may provide a prognostic preoperative screening method for varicocele infertile patients.

Genetic studies in varicocele infertility: I: pedigree, nuclear sex and seminal nucleic acids

The hereditary predisposition of varicocele men to develop infertility was investigated in a controlled study involving 30 infertile varicocele patients. Analysis of the pedigree charts, determination of sex chromatin constitution, and biochemical measurement of seminal nucleic acid (DNA/RNA) were undertaken. Sibs and Kins of infertile varicocele patients showed various developmental anomalies particularly of the genito-crural area. cocele formation while the gonads develop in the normal line. Such condition may be represented in fertile men with clinically detectable varicocele. In addition, the postulated defective gene in VI patients may interfere as well with the normal development of the mesenchyme-derived interstitial cells of Leydig. Defective testicular steroid hormone biosynthesis thus obtained may explain the reported decrease in androgen level in peripheral blood, sexual impotentia and accessory genital gland dysfunction (Raboch and Starka - 1971; Comhaire and Vermeulen - 1975). Moreover, being androgen dependent (Lacy - 1973), spermatogenesis may display abnormal patterns due to lowered intratesticular androgen concentration (Rodriguez-Rigau et al. - 1978). The outcome and severity of spermatogenic derangement may depend partially on the severity of disordered androgen biosynthesis. The present work showed significant decrease in sperm count, motility, normal forms and nucleic acid content (DNA and RNA) of the seminal fluid in VI patients. The decrease in the amount of DNA per millilitre of seminal fluid in VI patients may be explained by the decrease in sperm population (oligozoospermia). The decrease in the amount of RNA per millilitre of seminal fluid in VI patients may be due to the total decrease in cellular content of the seminal fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Histocompatibilty-linked susceptibility for hepatospleenomegaly in human schistosomiasis mansoni

In schistosomiasis mansoni, the pathogenesis of hepatosplenic disease has been shown to be due primarily to immune mechanisms. The present study was designed to examine the relationship between the development of schistosomal hepatosplenomegaly in Egyptian school children and the HLA antigens. Two groups of schistosome-infected children with similar fecal egg counts were examined: one group (23 children) had no clinically demonstrable hepatosplenomegaly whereas all the children (28) in the second group suffered from liver enlargement. Furthermore, 13 of the 28 individuals in the latter group had splenomegaly as well. Our results show that hepatosplenomegaly was related to the presence of two HLA antigens: HLA AI and B5. The average relative risk of developing hepatomegaly is 29 for HLA AI and 18.9 for 55.6. Furthermore, the severity of hepatomegaly was correlated with the presence of these two HLA antigens. These findings represent a step toward elucidating the factors controlling the pathogenic mechanisms in human schistosomiasis mansoni.

Histocompatibility-Linked Susceptibility for Hepatosplenomegaly in Human Schistosomiasis Mansoni

In schistosomiasis mansoni, the pathogenesis of hepatosplenic disease has been shown to be due primarily to immune mechanisms. The present study was designed to examine the relationship between the development of schistosomal hepatosplenomegaly in Egyptian school children and the HLA antigens. Two groups of schistosome-infected children with similar fecal egg counts were examined: one group (23 children) had no clinically demonstrable hepatosplenomegaly whereas all the children (28) in the second group suffered from liver enlargement. Furthermore, 13 of the 28 individuals in the latter group had splenomegaly as well. Our results show that hepatosplenomegaly was related to the presence of two HLA antigens: HLA A1 and B5. The average relative risk of developing hepatomegaly is 29 for HLA A1 and 18.9 for B5 and in the presence of both antigens it increases to 55.6. Furthermore, the severity of hepatomegaly was correlated with the presence of these two HLA antigens. These findings represent a step toward elucidating the factors controlling the pathogenic mechanisms in human schistosomiasis mansoni.