Serum levels of soluble interleukin-2 receptor in patients with ANCA-associated vasculitis

Serum soluble interleukin-2 receptor (sIL-2R) concentrations were determined using the ELISA method in 19 cases of ANCA-associated vasculitis. These patients were classified as 7 cases of Wegener's granulomatosis (WG) and 12 cases of microscopic polyangiitis (MPA). Elevated levels of sIL-2R were present in the sera of these patients. Levels of serum sIL-2R were not significantly different in patients with WG and MPA either in the active or inactive phase, so the results were expressed as a unified ANCA associated vasculitis group. Concentrations of serum sIL-2R were significantly higher in ANCA-associated vasculitis during the active phase than during the inactive phase (p<0.05), and serum sIL-2R levels were significantly increased in these patients, in the active or inactive stage, compared with a group of healthy subjects (p<0.05). In patients with vasculitis, serum sIL-2R levels correlated with serum levels of C-reactive protein (p<0.05). In the active phase, concentrations of serum sIL-2R correlated to creatinine concentrations. No correlation was found between sIL-2R and ANCA levels in any of the stages of the disease. These findings suggest cellular immune activation in ANCA associated vasculitis.

[Mutational analysis of the PKD1 and PKD2 (type 1 and 2 dominant autosomal polycystic kidney) genes]

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. It is caused by mutations in at least two different genes: PKD1 and PKD2. The study of mutations in these genes is very difficult nowadays. In this study we have analyzed the non reiterated region of the PKD1 gene and all the exons and intron exon boundaries of the PKD2 gene. The technique used to study these genes have been single strand conformation analysis and heteroduplex. We have found 25 differences within the DNA sequence of the PKD1 gene with respect to the published sequence. Seven of these changes correspond to nonsense, missense, frameshifting and splicing mutations. The rest of changes correspond to polymorphisms or rare DNA variants. In the PKD2 gene we have identified 8 new mutations and one polymorphism. Six of these mutations are frameshifting, one is missense and the other one is a large deletion of the PKD2 gene. The rate of mutation detection within the PKD1 gene has been 4% and the rate for PKD2 has been 100%. We have not observed any correlation between genotype and phenotype either in the PKD1 nor in the PKD2 gene. The mutation analysis of ADPKD genes is very difficult, specially for the PKD1 gene. The rate of mutation detection is higher in the PKD2 gene but the global efficacy of the technique is very low as PKD2 represents only 15% of ADPKD patients. Nowadays linkage analysis is still the most useful technique for the molecular diagnosis of ADPKD patients.

[Anti-glomerular basement membrane disease: a new disease causing fever of unknown origin?]

Antiglomerular basement membrane disease is an autoimmune disorder characterized by the presence of antibodies directed against glomerular basement membrane. Pyrexia of unknown origin (PUO) is defined as temperatures higher than 38.3 degrees C on several occasions, with a duration of more than 3 weeks, and failure to reach a diagnosis despite 1 week of in-patient investigation. There is a large list of causes of PUO including infections, malignancies and autoimmune diseases, but antiglomerular basement disease has not been described as a cause. We present the first case of antiglomerular basement disease which presented with PUO.

High prevalence of TT virus (TTV) infection in patients on maintenance hemodialysis: frequent mixed infections with different genotypes and lack of evidence of associated liver disease

Recently, a novel DNA virus, TT virus (TTV), was identified in patients with post-transfusion non-A-G hepatitis. We analyzed the prevalence and clinical implications of TTV infection in a cohort of 96 Spanish patients on long-term hemodialysis. TTV DNA was detected by nested PCR in 51 (53%) of 96 patients, a prevalence significantly higher than that found in healthy blood donors. Persistent liver test abnormalities were found in only 2 (7.7%) of 26 patients infected with TTV alone, compared with 12 (75%) of 16 patients infected with hepatitis C or hepatitis B virus, or both (P < 0.01). Mixed infections with multiple strains of TTV, including different major genotypes, were common in patients on hemodialysis. These patients had received a significantly greater number of blood units (22.7 +/- 20) compared with patients apparently infected with a single strain of TTV (8.9 +/- 11) (P = 0.01). Phylogenetic analyses of TTV from infected patients identified strains of genotypes 1, 2, 3, and 4. In summary, TTV infection was common in patients on hemodialysis but was not associated with liver disease

Autosomal dominant polycystic kidney disease types 1 and 2: assessment of US sensitivity for diagnosis

PURPOSE

To estimate the sensitivity and specificity of ultrasonography (US) in the diagnosis of autosomal dominant polycystic kidney disease (ADPKD) types 1 and 2, as compared with those of genetic linkage analysis.

MATERIALS AND METHODS

A renal US and DNA analysis for ADPKD was performed in 319 patients who were at risk, 161 of whom were younger than 30 years, from 54 families with ADPKD. The sensitivity of US for diagnosis was estimated by comparing the US results with genotypes inferred from linkage studies.

RESULTS

The sensitivity of US in individuals younger than 30 years who were at risk was 95% for ADPKD type 1 but only 67% for ADPKD type 2. The sensitivity of US for either ADPKD type 1 or ADPKD type 2 in individuals aged 30 years or older who were at risk was 100%. The overall sensitivity in individuals younger than 30 years was 93%. For both ADPKD types 1 and 2 in all patients, US demonstrated a sensitivity of 97%, a specificity of 100%, and an accuracy of 98%.

CONCLUSION

US is the first-line imaging technique that should be used in the diagnosis of ADPKD. The sensitivity in individuals aged 30 years or older is 100%, but if there is a clinical suspicion of ADPKD type 2 in individuals younger than 30 years, linkage analysis should also be considered.

Influence of the ACE gene polymorphism in the progression of renal failure in autosomal dominant polycystic kidney disease

The recent description of a polymorphism in the gene for angiotensin-converting enzyme (ACE), with the D allele associated with greater plasma levels of ACE, allows us to perform studies of the relationship between this polymorphism and chronic renal diseases in which the renin-angiotensin system could be implicated. We examined 155 patients with autosomal dominant polycystic kidney disease (ADPKD) with linkage to the PKD1 locus. The ACE insertion/deletion (I/D) polymorphism was amplified with the previously published flanking primers, and the polymerase chain reaction product was separated, sized on a 2% agarose gel, and visualized by ultraviolet transillumination. The ACE genotype distributions were 11.6%, 63.8%, and 24.5% for II, ID, and DD, respectively. There were no significant differences among the three genotypes with respect to mean age, sex distribution, and prevalence of hypertension. The ACE genotype distribution in patients with end-stage renal failure at the time of data compilation was similar to that of the entire study population. In the subgroup of patients who received renal replacement therapy before the age of 50 years, we found a significant association between DD genotype and onset of end-stage renal disease (ESRD) before the age of 50 years compared with II and ID (P = 0.017). We calculated the estimated median renal survival time as 51 years for the II genotype, 53 years for the ID genotype, and 48 years for the DD genotype. There were statistically significant differences between DD and ID patients (P = 0.025). In conclusion, we found DD genotype implies a worse renal prognosis based on both the significantly lower median renal survival time and significantly greater percentage of patients who reach ESRD before the age of 50 years, without implying a greater prevalence of hypertension.

A loss-of-function model for cystogenesis in human autosomal dominant polycystic kidney disease type 2

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous, with at least three chromosomal loci (PKD1, PKD2, and PKD3) that account for the disease. Mutations in the PKD2 gene, on the long arm of chromosome 4, are expected to be responsible for approximately 15% of cases of ADPKD. Although ADPKD is a systemic disease, it shows a focal expression, because <1% of nephrons become cystic. A feasible explanation for the focal nature of events in PKD1, proposed on the basis of the two-hit theory, suggests that cystogenesis results from the inactivation of the normal copy of the PKD1 gene by a second somatic mutation. The aim of this study is to demonstrate that somatic mutations are present in renal cysts from a PKD2 kidney. We have studied 30 renal cysts from a patient with PKD2 in which the germline mutation was shown to be a deletion that encompassed most of the disease gene. Loss-of-heterozygosity (LOH) studies showed loss of the wild-type allele in 10% of cysts. Screening of six exons of the gene by SSCP detected eight different somatic mutations, all of them expected to produce truncated proteins. Overall, >/=37% of the cysts studied presented somatic mutations. No LOH for the PKD1 gene or locus D3S1478 were observed in those cysts, which demonstrates that somatic alterations are specific. We have identified second-hit mutations in human PKD2 cysts, which suggests that this mechanism could be a crucial event in the development of cystogenesis in human ADPKD-type 2.

Seven novel mutations of the PKD2 gene in families with autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous, with at least three chromosomal loci accounting for the disease. Mutations in the PKD2 gene on the long arm of chromosome 4 are expected to be responsible for approximately 15% of cases of ADPKD.

METHODS

We report a systematic screening for mutations covering the 15 exons of the PKD2 gene in eight unrelated families with ADPKD type 2, using the heteroduplex technique.

RESULTS

Seven novel mutations were identified and characterized that, together with the previously described changes, amount to a detection rate of 85% in the population studied. The newly described mutations are two nonsense mutations, a 1 bp deletion, a 1 bp insertion, a mutation that involves both a substitution and a deletion (2511AG-->C), a complex mutation in exon 6 consisting of a simultaneous 7 bp inversion and a 4 bp deletion, and the last one is a G-->C transversion that may be a missense mutation. Most of these mutations are expected to lead to the formation of shorter truncated proteins lacking the carboxyl terminus of PKD2. We have also characterized a frequent polymorphism, Arg-Pro, at codon 28 in this gene. The clinical features of these PKD2 patients are similar to the previously described, with the mean age of end-stage renal disease being 75.5 years (SE +/- 3.8 years).

CONCLUSIONS

Our results confirm that many different mutations are likely to be responsible for the disease and that most pathogenic defects probably are point or small changes in the coding region of the gene.

Relationship between ANCA and disease activity in small vessel vasculitis patients with anti-MPO ANCA

BACKGROUND

We analysed the usefulness of antineutrophil cytoplasmic antibodies (ANCA) as a marker of clinical activity in patients with small vessel vasculitis associated with anti-myeloperoxidase (MPO) ANCA.

METHODS

We studied a group of 25 patients, 15 with microscopic polyangitis and 10 with renal limited vasculitis, so-called rapidly progressive glomerulonephritis type III. The clinical and serological follow-up was accomplished quarterly over an average of 2.79 +/- 2.08 years (range 0.25-6 years). ANCA was analysed by indirect immunofluorescence and enzyme-linked immunosorbent assays (ELISAs).

RESULTS

At the time of diagnosis, all patients were ANCA positive (P-ANCA and anti-MPO). Following a standardized treatment, all patients except one achieved complete remission of vasculitis in <3 months. One patient suddenly died during the active phase (1 month of follow-up) and with positive ANCA. Seroconversion from positive to negative occurred in 24/25 patients (96%). Eighteen of these 24 patients (75%) achieved the seroconversion within the first 6 months. During the follow-up, two patients had four major relapses, all of them associated with positive ANCA. ANCA seroconversion from negative to positive was observed in one patient with microscopic polyangitis without clinical relapse of vasculitis.

CONCLUSION

ANCA should be used in conjunction with other markers of disease activity in the management of microscopic polyangitis and renal limited vasculitis patients with anti-MPO ANCA.

[Genetic polymorphisms of the renin-angiotensin system and essential hypertension]

BACKGROUND

The renin-angiotensin system (RAS) plays an important role in blood pressure (BP) regulation. A number of RAS polymorphisms have been linked to essential hypertension (EH), but there is uncertainty about this association in other studies. We examined whether the insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene, and the M235T and T174M polymorphisms of the angiotensinogen (AGT) gene are associated with EH in a Spanish sample of hypertensive patients.

MATERIAL AND METHODS

We studied 75 patients with EH (BP > 160/100 mmHg), aged 55 (8.5) years, 30 males, systolic BP (SBP) 182 +/- (22.1) mmHg, diastolic BP (DBP) 109 +/- (9.9) mmHg (mean [SD]) and a strong family history of the disease. As a control group, 75 healthy subjects with no family history of cardiovascular disease were studied. The polymorphisms were determined by PCR amplification of genomic DNA, followed by enzyme digestion for the AGT gene polymorphisms.

RESULTS

The genotype distribution and the frequencies of the alleles of the three RAS polymorphisms were similar in hypertensive and control subjects. In addition, we did not find any compound effect of the I/D ACE gene and M235T AGT gene polymorphisms on BP levels in hypertensive and control subjects.

CONCLUSIONS

In this sample, the contribution of the ACE I/D polymorphism and the AGT M235T and T174M polymorphisms in the development of EH seems to be less important than previously estimated.

Effect of catecholamine depletion on lithium-induced long-term remission of bipolar disorder

BACKGROUND

This study investigated the effects of catecholamine depletion with alpha-methylparatyrosine (AMPT) on mood indices in patients with bipolar disorder who were in long-term remission with lithium therapy.

METHODS

Eight subjects with DSM-IV bipolar disorder currently in remission for > 3 months on lithium were included in the study. Subjects were given either AMPT or placebo, in a randomized double-blind manner, in two test sessions of 4 days each.

RESULTS

Subjects did not have any significant changes in mood during AMPT or placebo administration; however, 24-48 hours after the last active AMPT dose subjects had a transient relapse of hypomanic symptoms. Relapse of hypomanic symptoms did not correlate with increases in serum levels of homovanillic acid or 3-methoxy-4-hydroxyphenylglycol.

CONCLUSIONS

These findings suggest that the mechanism of prevention of manic relapse by long-term lithium therapy may be dependent on stability of the catecholamine system.

Mutational analysis within the 3' region of the PKD1 gene

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic diseases in humans, affecting 1 out of 1000 individuals. At least three different genes are involved in this disease. The search for mutations in PKD1 is complicated because most of the transcript is encoded by a genomic region reiterated more proximally on chromosome 16, and no prevalent mutation has been reported.

METHODS

We have screened DNA from exon 43 through exon 46 and intron 40 of the PKD1 sequence by single-stranded conformational polymorphism (SSCP) analysis in 175 ADPKD patients.

RESULTS

We have found 25 differences with respect to the reported PKD1 DNA sequence, seven of which are mutations (Q4041X, Q4124X, IVS44-1G-->C, IVS45-1G-->A, 12801del28, R4275W, and Q4224P). We found different phenotypical expressions of the same mutation in the families studied. We have detected several common polymorphisms, and some of them cosegregate, suggesting a common origin of these alleles in PKD1.

CONCLUSIONS

The detection of only seven mutations in 175 unrelated ADPKD patients for this region of the PKD1 analyzed suggests that mutations could be widespread throughout all of the gene and that a prevalent mutation is not expected to occur. The identified PKD1 missense mutations may help to refine critical regions of the protein. Until a quicker and more sensitive method for the detection of mutations becomes available, linkage studies will continue to be the basis for the molecular diagnosis of ADPKD families.

Primary lymphoma of the breast: MR imaging features. A case report

Primary non-Hodgkin's lymphoma (NHL) of the breast are rare and represent less than 0.6% of all mammary malignancies. Secondary involvement of the breast in patients with diffuse disease occurs more frequently. The radiologic features of breast lymphoma are nonspecific, and the diagnosis is based on histologic criteria. We present the MR-imaging features of a case of primary NHL of the breast.

Autosomal recessive Alport syndrome: linkage analysis and clinical features in two families

BACKGROUND

Genetic heterogeneity is a well-known feature of Alport syndrome (AS). Most families with AS show an X-linked dominant pattern of inheritance but about 15% of families show an autosomal inheritance of the disease. Autosomal recessive AS may account for 10% of the total number of cases and is caused by mutations in the COL4A3 and COL4A4 genes. The clinical spectrum of this rare disorder has not been well clarified.

METHODS

We present two families with AS. Two affected members of these families have entered end-stage renal disease (ESRD) in their 30s, and the other three are older than 15 years and have normal serum creatinine. Four of the five patients have deafness but none have ocular abnormalities. Two have been transplanted and have not suffered from anti-GBM antibody nephritis. Men and women are equally affected. We have performed linkage analysis for chromosome 2 with the following markers: D2S279, COL4A3/4 DNTR, COL4A4 RFLP Hae III.

RESULTS

We demonstrate that both families, one of them consanguineous, are linked to the COL4A3/4 locus.

CONCLUSIONS

We can conclude that the only significant difference between the X-linked and the autosomal recessive forms of AS lies in the fact that in the latter females are as affected as males; thus the idea that autosomal recessive AS causes ESRD during childhood must be discarded. Other clinical features such as age of deafness or the presence of post-transplant anti-GBM antibody nephritis show no differences between the entities. Thus an accurate familial study is mandatory in patients with AS, as the identification of the different patterns of inheritance may cause a great difference in genetic counselling. Linkage analysis is the only effective molecular diagnosis that can be performed nowadays.

Enhancement of intramammary lymph nodes with lymphoid hyperplasia: a potential pitfall in breast MRI

We present three cases of breast lesions labeled as probable intramammary lymph nodes that showed an increase in size on follow-up mammography. Contrast-enhanced MRI was performed and the three lesions showed strong and rapid uptake of the intravenous contrast. Core needle biopsy established the diagnosis of lymphoid hyperplasia in all three patients. Because intramammary lymph nodes affected by benign processes can present findings similar to malignant lesions, the usefulness of contrast-enhanced MRI in these cases is controversial.

[Usefulness of anti-neutrophil cytoplasmic antibodies, anti-proteinase 3 and anti-myeloperoxidase in management of small vessel vasculitis]

BACKGROUND

Analysis of usefulness of antineutrophil cytoplasmic antibodies (AN-CA) as a marker of clinical activity in small vessel vasculitis.

PATIENTS AND METHODS

33 patients, 10 patients with Wegener's granulomatosis (WG) and 23 with microscopic polyangiitis (MPA) and rapidly progressive glomerulonephritis type III (RPGN III). The clinic and serologic follow-up was accomplished every 3 months during an average of 19 (SD, 24) months (range 3-52 months. The serologic follow-up included the determination of ANCA by indirect immunofluorescence (IFI) and ELISA, as well as the serum level of C reactive protein (RCP).

RESULTS

At the time of diagnosis all patients were ANCA positive by IFI and ELISA. The seroconversion of ANCA from positive to negative was produced in 30/33 patients (90%). Twenty-six out of these 30 patients (87%) achieved the seroconversion within the first 6 months. During the follow-up 4 patients had a major relapse, all with positive ANCA. In 2 patients, one of each group, seroconversion from negative to positive was not associated with clinical relapse of vasculitis.

CONCLUSION

ANCA should be used in conjunction with other indices of disease activity in patients with small vessel vasculitis.

Renal failure in multiple myeloma: presenting features and predictors of outcome in 94 patients from a single institution

BACKGROUND

Twenty percent of patients with multiple myeloma (MM) have renal failure.

OBJECTIVE

To analyze the presenting features, the response to therapy, and the factors associated with renal function recovery and survival in 94 patients with MM and renal failure.

PATIENTS AND METHODS

Medical records of patients from our institution with MM and renal failure diagnosed between January 1969 and December 1994 were reviewed. The statistical methods consisted of Kaplan-Meier survival curves, the log-rank test, logistic regression analysis, and the Cox proportional hazards model for survival analysis.

RESULTS

Renal failure was observed in 94 (22.2%) of 423 patients. Patients with renal failure had more advanced disease than the others. Patients with renal failure had a lower response rate to chemotherapy than those with normal renal function (39% vs 56%; P<.001). However, when patients dying within the first 2 months of treatment were excluded, no significant differences in the response rate were found between patients with renal failure and those with normal renal function. Renal function recovery was observed in 26% of patients. Serum creatinine level (<354 micromol/L [<4 mg/dL]), serum calcium level (> or =2.88 mmol/L [> or = 11.5 mg/dL]), and amount of proteinuria (< 1 g/24 h) were associated with renal function recovery. Patients who recovered renal function had a median survival of 28 months vs 4 months for those with nonreversible renal failure (P<.001). In the multivariate analysis, only serum creatinine level (P=.003) and response to chemotherapy (P<.001) were correlated with survival.

CONCLUSIONS

Renal failure was present in almost one fourth of patients with MM. Patients with reversible renal failure had longer survival than those not recovering renal function. When patients dying within the first 2 months of treatment were excluded, the response rate was not affected by renal function. Factors associated with renal function recovery were degree of renal failure, presence of hypercalcemia, and amount of proteinuria. Response to chemotherapy and severity of renal failure were the only independent factors associated with survival.

Facilitated diagnosis of the contiguous gene syndrome: tuberous sclerosis and polycystic kidneys by means of haplotype studies

Tuberous sclerosis (TSC) and autosomal dominant polycystic kidney disease (ADPKD) are genetically heterogeneous diseases. The major gene for ADPKD (PKD1) lies adjacent to the TSC2 gene on chromosome 16p13. Some reports in the literature referred to an unusual presentation of TSC with enlarged cystic kidneys at birth, but it was not until the localization of the TSC2 and PKD1 genes that it was possible to analyze the interaction between both genes. We describe a case of a child with TSC and enlarged cystic kidneys. The study of genetic marker segregation in the family pointed to the presence of a deletion involving the 3' region of PKD1. A further study of the region showed a deletion of 40 kb involving both PKD1 and TSC2. We suggest that an additive or synergistic effect between PKD1 and TSC2 may cause this renal phenotype. A contiguous gene syndrome involving PKD1 and TSC2 should be suspected in children with TSC and enlarged polycystic kidneys at birth. The first approach to identify a deletion of both genes could be the analysis of the segregation of PKD1 and TSC2 markers in the family.

Angiotensin converting enzyme gene I/D polymorphism in essential hypertension and nephroangiosclerosis

An insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene significantly influences circulating ACE levels and plays a role in the development of target organ damage, that is, left ventricular hypertrophy in essential hypertension (EH), and microalbuminuria in diabetes mellitus. We have examined the role of the I/D polymorphism in essential hypertensive patients with renal involvement. The study was divided in two independent protocols. In protocol 1, we retrospectively analyzed the ACE genotypes in 37 essential hypertensive patients with a clinical and histopathological diagnosis of nephroangiosclerosis. In protocol 2, ACE genotypes as well as microalbuminuria and renal hemodynamic parameters were investigated in 75 patients with EH with normal renal function and a strong family history of hypertension. As control group, 75 healthy subjects with BP < 130/85 mm Hg and no family history of cardiovascular diseases were studied. The ACE variants were determined by PCR and the genotypes were classified as DD, DI and II. In protocol 1, patients with nephroangiosclerosis displayed a significant difference in the genotype distribution (57% DD, 27% DI, 16% II) when compared to the control population (25% DD, 64% DI, 11% II; P < 0.001). There was no significant difference in genotype distribution between hypertensive patients with normal renal function (protocol 2; 33% DD, 59% DI, 8% II) and the control group. There were no differences in age, blood pressure, microalbuminuria and duration of the disease among the three genotypes in the EH group from protocol 2. Taken together, these findings suggest that the DD genotype of ACE is associated with histopathologic-proven kidney involvement in patients with EH and that this polymorphism could be a potential genetic marker in hypertensives at risk of renal complications.

Hyperechoic liver nodules: characterization with proton fat-water chemical shift MR imaging

PURPOSE

To evaluate proton fat-water chemical shift fast low-angle shot magnetic resonance (MR) imaging for differentiation of fat-containing hyperechoic liver nodules from hyperechoic liver nodules without a fatty component.

MATERIALS AND METHODS

T1-weighted fast low-angle shot fat-water chemical shift gradient-echo MR imaging was performed in 96 patients without cirrhosis with 138 hyperechoic liver nodules. In-phase and opposed-phase breath-hold images were acquired. The percentage of signal intensity variation between in-phase and opposed-phase images and the spleen-to-lesion contrast ratio were used to differentiate liver nodules.

RESULTS

Chemical shift MR images showed fat in 15 (11%) hyperechoic nodules (two angiomyolipomas and 13 nodular fatty infiltrations of the liver). The mean percentage of signal intensity variation between in-phase and opposed-phase images was 156% (standard error, 43.5%) in nodules with fat and -0.16% (standard error, 0.96%) in nodules without fat (P = .003). Spleen-to-lesion contrast was similar on in- and opposed-phase images in lesions without fat (mean difference, -0.0107; standard error, 0.012), whereas the mean difference in fat-containing nodules was 0.805 (standard error, 0.225; P = .003). The area under the receiver operating characteristic curve was 0.97 for signal intensity variation.

CONCLUSION

Hyperechogenicity in certain liver nodules is caused by fat. Chemical shift MR imaging allows accurate differentiation between these and other hyperechoic lesions with no fat component.

[Clinical, genetic and molecular studies on autosomal dominant polycystic kidney disease]

BACKGROUND

Two genes causing autosomal dominant polycystic kidney disease (ADPKD), PKD1 and PKD2, have been described. In the present work we study, by means of linkage analysis, the genetic heterogeneity in our population as well as the clinical differences between PKD1 and PKD2.

SUBJECTS AND METHODS

316 subjects belonging to 49 unrelated ADPKD families have been studied by means of 3 microsatellites for PKD1 and 3 for PKD2 to differentiate if they have ADPKD type 1 or 2. The techniques used to analyze the microsatellites have been the chemiluminescence and the silver satining techniques. All the subjects underwent a complete physical examination and a sonographic scan. Clinical and molecular results have been correlated.

RESULTS

Genetic heterogeneity has been proved, with 85% of families linked to PKD1 and 15% to PKD2. The disease is more severe in PKD1, with an earlier age at diagnosis (27.4 vs. 41.4 years; p = 0.0002), a younger age at the onset of end stage renal disease (53.4 vs. 72.7 years, p < 0.00001), and earlier age at diagnosis of hypertension (34.8 vs. 49.7 years; p = 0.001) and a higher prevalence of hypertension for all groups of age. In both forms of ADPKD there were families showing anticipation (8/44 for PKD1 and 2/5 for PKD2) but this was not a widespread phenomenon. Our data do not support the phenomenon of genetic imprinting for this disease.

CONCLUSION

In the population of Catalonia, Spain, PKD1 accounts for 85% of families with autosomal dominant polycystic kidney disease and PKD2 accounts for the remaining 15%. PKD1 form is more severe than PKD2.