Haemochromatosis gene mutations Cys282Tyr and His63Asp are not increased in Type 2 diabetic patients compared with the Canterbury (New Zealand) general population.

Genetic predisposition to haemochromatosis may be an important aetiological factor in some cases of Type 2 diabetes. Our aim was therefore to test the hypothesis that the haemochromatosis gene mutations Cys282Tyr and His63Asp are more prevalent in Type 2 diabetic patients compared with the Canterbury, New Zealand general population. We studied 230 consecutive patients referred to the Diabetes Services with age > or = 30 years and considered to have Type 2 diabetes. DNA was extracted from whole blood and amplified by polymerase chain reaction prior to restriction fragment length polymorphism analysis. The frequency of the mutations was compared with that observed previously in 1064 subjects from the Canterbury general population by chi2 testing. Iron was measured by a colorimetric method, transferrin by rate nephelometry and ferritin by immunoassay. There were 2/230 (0.8%) Cys282Tyr homozygous subjects in the diabetic group compared with 5/1064 (0.5%) NS in the general population. Although there was a trend to lower incidence of Cys282Tyr heterozygosity in the diabetic group, there was no significant difference for any of the six genotype frequencies between the two groups. Haemochromatosis gene mutations Cys282Tyr and His63Asp are therefore not increased in Type 2 diabetics compared with the general population. Transferrin saturation was a sensitive marker (100%) of genetic haemochromatosis, although ferritin had low specificity (77.8%). Genetic susceptibility to haemochromatosis is not an important aetiological factor for diabetes, and targeted screening of diabetic patients for haemochromatosis is not indicated.

The significance of haemochromatosis gene mutations in the general population: implications for screening.

BACKGROUND: Haemochromatosis is associated with mutations in the HFE gene but the significance of these mutations in the general population is unknown. AIMS: To determine the frequency of HFE gene mutations in the general population, their effect on serum iron indexes, and their role in screening for haemochromatosis. METHODS: Deoxyribonucleic acid (DNA) from 1064 randomly selected subjects was analysed for the C282Y and H63D mutations in the HFE gene. Serum iron, transferrin saturation, and ferritin were measured and individuals with increased iron indexes were investigated to confirm or exclude a clinical diagnosis of haemochromatosis. RESULTS: Mutations were identified in 409 individuals (38.4%) with heterozygote (carrier) frequencies of 13.2% and 24.3% for the C282Y and H63D mutations respectively. Heterozygosity for either mutation significantly increased serum iron and transferrin saturation but despite a similar trend for ferritin, this was only significant for C282Y homozygotes. Five individuals (0.47%) were homozygous for the C282Y mutation, three of whom had haemochromatosis confirmed by liver biopsy (0.28%). The other two C282Y homozygotes would not have been detected by phenotypic screening alone. CONCLUSIONS: HFE mutations are present in 38.4% of the population, affect serum iron indexes, and are important determinants of iron status. The population frequency of genetically defined haemochromatosis (C282Y homozygosity) is approximately one in 200 and is higher than the prevalence of clinically apparent haemochromatosis.

Molecular analysis of HLA-H gene mutations in New Zealand patients with haemochromatosis.

AIM: To determine the frequency of HLA-H gene mutations in New Zealand patients with haemochromatosis. METHODS: The Cys282Tyr and His63Asp mutations in the HLA-H gene were analyzed by polymerase chain reaction, restriction enzyme digestion and electrophoresis in two separate patient groups. The first was a group of 20 Christchurch patients with a definite clinical diagnosis of haemochromatosis. The second group consisted of 33 patients, with a provisional diagnosis of haemochromatosis, attending Dunedin Hospital for therapeutic venesection. RESULTS: All 20 Christchurch patients and 25 of the 33 (76%) Dunedin patients were homozygous for the Cys282Tyr mutation. After review of the clinical data, histology and response to venesection a diagnosis of haemochromatosis could be confidently excluded in six of the remaining eight patients. Despite atypical features, a diagnosis of haemochromatosis could not be excluded in the final two patients, one of whom was a compound heterozygote for the two mutations. CONCLUSIONS: Homozygosity for the Cys282Tyr mutation is closely associated with haemochromatosis in New Zealand patients. Molecular analysis of the HLA-H gene is indicated in the assessment of patients with iron overload including those currently being treated by venesection.

Huntington's disease: diagnosis by amplification of the CAG repeat.

AIM: To develop and validate a test for the diagnosis of Huntington's disease by the direct detection, and sizing of, expanded CAG triplet repeats within the Huntington gene of affected individuals. METHODS: A polymerase chain reaction-based test which specifically amplifies the CAG repeat was developed using an ultra heat stable polymerase and [alpha 35S] delta ATP incorporation. Amplified alleles were separated on DNA sequencing gels and sized by comparison with a known sequence. RESULTS: Analysis of 10 affected individuals showed abnormal alleles with repeat numbers ranging from 40 to 61. In one case, that had been diagnostically uncertain because there was no family history of Huntington's disease, the demonstration of an expanded allele confirmed the diagnosis. Analysis of this patient's elderly and unaffected father indicated that he had an allele at the extreme end of the normal range. In a second case with atypical neurological features the diagnosis was also established by the demonstration of an expanded allele. CONCLUSIONS: This assay allows improved diagnosis of Huntington's disease including completely accurate presymptomatic and antenatal diagnosis. Easy access to this test has implications for clinical practice but acceptable guidelines for its use will need to be developed.

Nodular fasciitis of the bladder.

Nodular fasciitis is a nonneoplastic swelling consisting of fibroblastic proliferation and commonly occurring in the subcutaneous tissue of the extremities. We report a case of nodular fasciitis involving the wall of the bladder. It is important to be aware of the histological characteristics of this essentially benign condition so that unnecessary radical therapies can be avoided.

Synchronous bilateral surgery for calculous disease of the upper urinary tract.

Bilateral calculous disease of the upper urinary tract frequently poses great difficulty in therapeutic decisions. Staged or sequential surgery is often recommended, with the side that is more obstructed, infected, or symptomatic operated on first. Despite all the rationalization for sequential surgery, we believe that a simultaneous surgical approach to bilateral calculous disease is feasible and advisable in some situations. On the basis of our experience with nine patients, we have categorized the indications for such surgery. In patients, with bilateral calculous disease for whom surgical intervention on both sides will at some point be necessary, simultaneous single-stage surgery is recommended. This is especially true: (a) with bilateral obstructive calculi; (b) in bilateral calculous disease with acute pyelonephritis when which side is affected is equivocal; (c) when anatomic proximity makes bilateral surgery easier, e.g. in bilateral lower ureteral calculi or bilateral calculi in horseshoe kidneys.

Prophylactic antibiotics in transurethral resection of bladder tumors: are they necessary?

In a double-blind study, 30 patients having transurethral surgery for bladder tumors were randomly assigned to receive prophylactic carbenicillin indanyl sodium or a placebo perioperatively. Only one patient in the carbenicillin group had a postoperative urinary infection due to carbenicillin-resistant Klebsiella oxytoca organisms. Thus, no advantage from the prophylactic use of antibiotics was evident in this uninfected group of patients.

Benign intrascrotal neoplasms.

We analyzed the surgical and pathological records of 90 patients who underwent surgical exploration of solid scrotal masses during a 5-year period. Sixteen patients had benign lesions, including 10 adenomatoid tumors, 3 fibrous pseudotumors, 2 fibromas and 1 dermoid cyst. Twelve patients with benign lesions were treated by local excision and 4 by orchiectomy. Identification of benign intrascrotal lesions, aided by examination of frozen sections and combined with an understanding of the lesions, allows the intraoperative decision for local excision and the avoidance of needless orchiectomy.

Intravenous glucose tolerance tests in the New Zealand strains of mice.

Intravenous glucose tolerance tests (I.V.G.T.T.) were carried out in fasting NZO, NZB and NZB/W mice. NZO and NZB mice exhibited an impaired rate of glucose decay, while NZB/W mice cleared glucose very rapidly. The possibility that autoimmune processes are responsible for the glucose intolerance observed in NZO and NZB mice is discussed.

The effect of manganese on lipogenesis, lipolysis, adenosine 3',5' cyclic monophosphate and cyclic nucleotide phosphodiesterase activity in adipocytes from NZY mice.

The insulin-like action of Mn2+ was investigated in adipocytes isolated from male mice of the NZY strain. In agreement with previous reports Mn2+ was found to stimulate both the oxidation of [U-14C]glucose to CO2 and the incorporation of [U-14C]glucose into total lipid and fatty acid, and to inhibit lipolysis stimulated by epinephrine, cyclic AMP or theophylline. The maximum effect of Mn2+ was greater than that of a maximal concentration of insulin and when both agents were present in these concentrations the effect was similar to that observed with Mn2+ alone. Mn2+ lowered the level of cyclic AMP in adipocytes incubated with isoproterenol. The effect was seen as early as 1 minute and it was greater than a maximal concentration of insulin. When Mn2+ was added to suspensions of adipocytes it increased the activity of the membrane-bound low Km cyclic nucleotide phosphodiesterase in subsequently prepared homogenates. The enzyme was stimulated 1.8-fold by Mn2+ compared with a 1.7-fold stimulation by insulin and a 2-fold stimulation in the presence of both Mn2+ and insulin.

Is extracellular calcium required for insulin action?

Isolated hepatocytes and isolated adipocytes incubated in the absence of added calcium ions respond to insulin with a decrease in tissue cyclic AMP levels, and an increase in low Km phosphodiesterase activity. Isolated hepatocytes also showed a diminution of glucagon stimulated glucose output in response to insulin, while adipocytes responded with increased rates of glucose oxidation, lipid synthesis and decreased glycerol output. These responses to insulin are the same as those seen when the cells are incubated in buffers containing physiological concentrations of calcium ions. When extracellular concentrations of calcium ions were made extremely low by using either gelatine or albumin which had been pretreated to remove calcium, and/or the incubation buffers contained EGTA, both the hepatocytes and adipocytes continued to respond to insulin. These results suggest that extracellular calcium ions are not required for insulin action.