Acquired dysfibrinogenemia caused by monoclonal production of immunoglobulin lambda light chain.

Disorders of fibrinogen are usually caused by genetic mutations that result in low protein levels (hypofibrinogenemia) or an abnormal molecule (dysfibrinogenemia). However, environmental and plasma factors can have an acquired effect on its expression or function. For example, antibodies can bind fibrinogen and/or fibrin to interfere with polymerization and inhibit coagulation. The objective here was to determine the cause of dysfibrinogenemia in a 63-year-old man. Despite a low functional fibrinogen concentration and prolonged thrombin time, no inherited fibrinogen abnormality could be detected after extensive protein analysis and gene sequencing. Thus, electrophoresis methods and fibrinogen binding studies were used to establish the cause of the acquired dysfibrinogenemia. An immunoglobulin lambda light chain was found to bind fibrinogen as a monomer. It had no significant effect on fibrinopeptide release, but caused substantial defects in all other stages of thrombin-catalyzed fibrin polymerization. Binding to fibrinogen also seemed to prevent the light chain from being filtered through the kidneys, causing only low levels of it in the urine. Once in the urine, the lambda chain lost its anti-fibrinogen activity, apparently due to dimerization. The 63-year-old patient acquired dysfibrinogenemia from a monoclonal production of lambda light chain that bound and inhibited the function of fibrinogen. At age 64.5 he was diagnosed with monoclonal gammopathy of undetermined significance, explaining the abnormal immunoglobulin chain production. This case was particularly unusual in that the inhibition of fibrin polymerization was caused by a single immunoglobulin light chain, rather than by a whole antibody molecule.

Dietary iron intakes and biochemical iron status of 15-49 year old women in New Zealand: is there a cause for concern?

AIM: To assess dietary iron intakes and biochemical iron status of a nationally representative sample of nonpregnant 15-49 year old women (n=1,751) in New Zealand. METHODS: A cross-sectional national survey was conducted in 1996/97. Women were selected via a multistage stratified cluster sampling procedure with increased sampling of Maori and Pacific women. Dietary iron intakes were estimated using a 24-hour diet recall. Biochemical iron status was assessed on a non-fasting venipuncture blood sample (n=1,047) via haemoglobin, mean cell volume, erythrocyte zinc protoporphyrin, transferrin receptors and serum ferritin. RESULTS: Average daily dietary iron intakes ranged from 9.6 mg/day among Pacific women to 10.5 mg/day among Maori women; 41% of 20-49 year olds and 45% of adolescents were at risk of low dietary iron intakes. The estimated percentage of 15-49 year old women with iron deficiency anaemia ranged from 1.4-5.5%, and for iron deficiency without anaemia from 0.7-12.6% depending on the age group and criteria used. CONCLUSIONS: The overall estimated prevalence of suboptimal biochemical iron status among 15-49 year old women in New Zealand ranged from 7-13%, which compared favourably with premenopausal women living in other western countries. This situation is, however, a public health concern given the potential negative functional consequences associated with even mild iron deficiency.

Hypofibrinogenemia in an individual with 2 coding (gamma82 A-->G and Bbeta235 P-->L) and 2 noncoding mutations.

We investigated the molecular basis of hypofibrinogenemia in a man with a normal thrombin clotting time. Protein analysis indicated equal plasma expression of 2 different Bbeta alleles, and DNA sequencing confirmed heterozygosity for a new Bbeta235 P-->L mutation. Protein analysis also revealed a novel gamma(D) chain, present at a ratio of 1:2 relative to the gamma(A) chain. Mass spectrometry indicated a 14 d decrease in the gamma(D)-chain mass, and DNA sequencing showed this was caused by a novel gamma82 A-->G substitution. DNA sequencing established heterozygosity for 2 further mutations: T-->C in intron 4 of the Aalpha gene and A-->C in the 3' noncoding region of the Bbeta gene. Studies on the man's daughter, together with plasma expression levels, discounted both the Aalpha and Bbeta mutations as the cause of the low fibrinogen, suggesting that the gamma82 mutation caused the hypofibrinogenemia. This was supported by analysis of 31 normal controls in whom the Bbeta mutations were found at polymorphic levels, with an allelic frequency of 5% for the Bbeta235 mutation and 42% for the Bbeta 3' untranslated mutation. The gamma82 mutation was, however, unique to the propositus. Residue gamma82 is located in the triple helix that separates the E and D domains, and aberrant packing of the helices may explain the decreased fibrinogen concentration. (Blood. 2000;95:1709-1713)

Rapid identification of an A1555G mutation in human mitochondrial DNA implicated in aminoglycoside-induced ototoxicity.

This article describes a multiplex allele-specific PCR (AS-PCR) approach for detection of an A to G mutation occurring in the human mitochondrial 12s RNA gene at nucleotide 1555. Possession of this mutation has been shown to be associated with irreversible hearing loss following administration of aminoglycoside antibiotics, and in some families is associated with profound sensorineural deafness in the absence of aminoglycoside antibiotics. We screened 206 unrelated individuals from the province of Otago, New Zealand, and found one who possessed the mitochondrial 1555 A to G mutation (0.48%; 95% confidence interval, 0.01-2.75).

Fibrinogen Otago: a major alpha chain truncation associated with severe hypofibrinogenaemia and recurrent miscarriage.

A woman with a preliminary diagnosis of afibrinogenaemia was later found to have a functional fibrinogen of 0.06 mg/ml and markedly prolonged thrombin and reptilase times. The stoichiometry of fibrinopeptide release was normal but there was a gross delay in the polymerization of purified fibrin. Plasma protein electrophoresis showed an absence of normal fibrinogen and a novel anodal component which was confirmed as fibrinogen by immunofixation. Western blots of non-reducing SDS-PAGE gels indicated a molecular weight of 270 kD, compared to 340 kD for normal fibrinogen and similar analysis of reducing gels showed that the expected 67 kD A alpha chain was missing and replaced by a 30 kD band. This aberrant chain was not detected by the monoclonal antibody F-103, which recognizes the epitope formed by residues 259-276 of the A alpha chain. Cycle sequencing of the DNA encoding the F-103 epitope revealed the homozygous insertion of cytosine at position 4133 of the gene sequence. Predictably this translates as three new amino acids (268Gln-Glu-Pro) before termination at a new (TAG) stop codon. No abnormal A alpha chains could be detected in plasma from the woman's heterozygous son. The hypofibrinogenaemia observed is likely to be the result of diminished assembly and/or secretion of the truncated A alpha chains rather than enhanced extracellular degradation.

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.

High-dose intravenous human immunoglobulin in chronic inflammatory demyelinating polyneuropathy.

We treated nine consecutive patients with chronic inflammatory demyelinating polyneuropathy (CIDP) with high-dose intravenous human immunoglobulin (HIG), and clinical recovery rapidly followed. Disability that had persisted for months or years was often reversed in days. There were no major adverse reactions to HIG infusions.

A child with Refsum's disease: successful treatment with diet and plasma exchange.

A child with Refsum's disease presented with cardiac failure, marked muscle wasting, weakness and inco-ordination. Management with multiple plasma exchanges and dietary restriction of phytanic acid intake has reversed the disabling features of the disease, although levels still remain higher than target values. Low phytanic acid intake is being achieved by restriction of total fat to 10 to 12 g/day, while allowing free amounts of fruit and green vegetables.

Cytomegalovirus infection and blood transfusion.

The incidence of cytomegalovirus antibody positivity has been determined in populations of blood donors in centres in the North and South Islands of New Zealand. No difference in incidence was found. Rates of antibody detection increased from approximately 30% in younger donors to approximately 65% in donors between the ages of 56 and 65 years. No sex difference in incidence was observed. The implications for policies governing the supply of cytomegalovirus antibody-free blood for transfusion are discussed.

Blood lead, intelligence, reading attainment, and behaviour in eleven year old children in Dunedin, New Zealand.

A study of blood lead levels and intelligence, reading, and behaviour problems was carried out using a sample of 579 Dunedin 11-yr-old children. The results suggested that when account was taken of social, environmental, and background factors, raised blood lead is associated with a small but statistically significant increase in children's general behaviour problems as reported by both parents and teachers. These results applied especially to the more specific problems of inattention and hyperactivity.

Non-steroidal anti-inflammatory drugs and platelet function.

The effect of some newer non steroidal inflammatory drugs on platelet function has been assessed using platelet malondialdehyde production as a measure of cyclooxygenase activity. After single doses of the short acting NSAID's diflunisal, naproxen and sulindac, platelet malondialdehyde production was substantially diminished at one and three hours. It had largely recovered by 24 hours and had returned to normal by 48 hours. After aspirin malondialdehyde production was markedly reduced and was still down at 72 hours. After the long acting NSAID piroxicam, in doses providing blood levels comparable with those in long term treatment, malondialdehyde production was still down at 72 hours.

Blood lead levels in Dunedin 11 year old children.

Blood lead levels were determined for 579 eleven year old children. The range of blood lead levels was from 0.19 to 2.41 mumol/l with a geometric mean of 0.49 mumol/l (geometric SD 0.07) and an arithmetic mean of 0.54 mumol/l (arithmetic SD 0.24). Two children had levels above 1.45 mumol/l. There was no significant correlation between blood lead levels and socio-economic status. Ten children with elevated blood lead levels (greater than 1.11 mumol/l) were reassessed and the results from all but one child had returned to a lower level. In nine out of ten of these cases recent inside paint stripping activities had been carried out in the child's home.