Intracranial calcification and seizures: a case of central neurofibromatosis

Periventricular calcification was found in an eight-year-old boy with seizures. The diagnosis of tuberous sclerosis was considered, but (like his mother) he has central neurofibromatosis. This condition must be considered in the differential diagnosis of children with intracranial calcification and seizures.

Possible genetic heterogeneity in X linked hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia has been mapped to Xq11-q13 by linkage studies and by a translocation in a manifesting female. We report a family with hypohidrotic ectodermal dysplasia in which the disease did not segregate with this region of the X chromosome as expected. Ten DNA probes which are localised between Xp11 and Xq22 were used in the investigation. The difficulties in diagnosing the carrier state in this condition and the possibility of non-allelic heterogeneity are discussed.

Mitochondrial genome: defects, disease, and evolution

Defects of mitochondrial function are often caused by defects of the mitochondrial genome. The hypothesis that defective organelles may spread through syncytial tissues as a result of a process of subcellular Darwinian selection is proposed. Tissues are likely to be involved in mitochondrial disease if they are syncytial, are derived from a few embryonic cells only, have little redundancy of function, and are subject to repeated metabolic stress. These effects, together with the random distribution of genetically heterogeneous mitochondria within the fertilised zygote, may account for the varied clinical pictures of mitochondrial disease. Evolution will have favoured the shift of mitochondrial DNA sequences to the nucleus, once the differentiation of tissues had created body compartments in which defective mitochondria could flourish to the detriment of the organism. This model of mitochondrial disease allows the generation of several predictions, testable using currently available laboratory techniques. Avenues of potential therapeutic value are indicated, including the avoidance of hypoglycaemia and the use of selective mitochondrial toxins.

X linked neonatal centronuclear/myotubular myopathy: evidence for linkage to Xq28 DNA marker loci

We have studied the inheritance of several polymorphic Xq27/28 DNA marker loci in two three generation families with the X linked neonatal lethal form of centronuclear/myotubular myopathy (XL MTM). We found complete linkage of XLMTM to all four informative Xq28 markers analysed, with GCP/RCP (Z = 3.876, theta = 0.00), with DXS15 (Z = 3.737, theta = 0.00), with DXS52 (Z = 2.709, theta = 0.00), and with F8C (Z = 1.020, theta = 0.00). In the absence of any observable recombination, we are unable to sublocalise the XLMTM locus further within the Xq28 region. This evidence for an Xq28 localisation may allow us to carry out useful genetic counselling within such families.

Abnormalities of carbohydrate metabolism and of OCT gene function in the Rett syndrome

The pathogenetic basis of the Rett syndrome (RS) is unknown: an X-linked dominant, male-lethal gene defect is thought likely. We present a girl with RS who has defects both of the urea cycle and of carbohydrate metabolism resulting in fasting hypoglycaemia, post-prandial hyperlactataemia and excess urinary orotic acid excretion after alanine load. Her sister has a similar clinical picture, but less marked metabolic anomalies. The mother of these sisters has abnormal urinary orotic acid excretion; she transmitted opposite ornithine carbomoyltransferase (OCT) alleles to the two girls. Another girl with RS has similar metabolic responses to fasting and to carbohydrate load. We conclude that RS may be an aetiologically homogeneous condition, but that it includes a variable pattern of metabolic anomalies, and that the gene defect is distinct from the OCT locus.

Improved diagnosis of Becker muscular dystrophy by dystrophin testing

We assessed the quantity (relative cellular abundance) and quality (approximate molecular weight) of dystrophin in muscle biopsies from 97 patients with a diagnosis of possible Becker muscular dystrophy. Fifty-four (all male) had dystrophin abnormalities and were deemed to have true Becker muscular dystrophy. The other 43 patients (14 female, 29 male) had no detectable dystrophin abnormalities. Of the dystrophin-verified Becker dystrophy patients, 35% (19/54) had a family history consistent with X-linked recessive inheritance. On the other hand, none of the 43 patients with apparently normal dystrophin had a clear X-linked family history, suggesting that few of these 43 actually had a form of Becker dystrophy. The data suggest that of all patients with a clinical picture consistent with Becker dystrophy but no family history, about 60% will be true Becker patients. The correlation of both the biochemical and clinical data suggests that Duchenne/Becker dystrophy can be divided into 4 clinically useful categories: Duchenne dystrophy (wheelchair at about age 11 years; dystrophin quantity less than 3% of normal); severe Becker dystrophy (wheelchair age 13 to 20 years; dystrophin 3% to 10%); and moderate/mild Becker dystrophy (wheelchair greater than 20 years; dystrophin quantity greater than or equal to 20%). Given the observed clinical variability of Becker dystrophy, it appears that dystrophin analysis is required for accurately distinguishing between Becker dystrophy and clinically similar autosomal recessive myopathies.

Population frequencies of three DNA alleles linked to the Duchenne muscular dystrophy gene

To enquire whether the known X linked probes linked to the Duchenne muscular dystrophy gene vary in their RFLP frequencies, three probes, 754, XJ1.1, and pERT87.8, were tested in European, Indian Muslim, and West African samples. Though the average heterozygosity for the three together is fairly similar in the three populations, significant differences in allele frequencies were evident.

Cervical receptors and the direction of body sway

A study was performed to determine whether the predominant direction of body sway is influenced by changes of head-to-trunk position. A group of ten patients suffering from acute unilateral vestibular loss was compared with a group of ten healthy subjects. Body sway was assessed by measurement on a posture platform. Center-of-force stabilograms were recorded with the subjects' eyes closed. After a baseline interval in the normal head-to trunk orientation, the head was torsioflexed with respect to the trunk and the locus of the center-of-force further assessed over a defined interval. It was observed that the patient group manifested a systematic translation of the direction of body sway that was associated in a consistent manner with the unilateral deficit. This translation occurred synchronously with head torsioflexion and could also be reproduced when turning the trunk with the head fixed, so that a semicircular canal influence could be excluded. It appears that cervical proprioceptive input to the central vestibular system is responsible for the effect observed.

Improved definition of carrier status in X-linked hypohidrotic ectodermal dysplasia by use of restriction fragment length polymorphism-based linkage analysis

The detection of carriers of the X-linked disorder hypohidrotic ectodermal dysplasia is problematic because of random X-inactivation; the diagnosis was previously based on the observation of subtle defects in ectodermal structures in at-risk females. Linkage studies have recently mapped hypohidrotic ectodermal dysplasia to the region Xq11-q21.1. We assessed the improvement in carrier detection by the method of linkage analysis, in which restriction fragment length polymorphisms were used as markers, in 72 at-risk female members of 29 families. Carriers analyses were based on pedigree information, dental examination of at-risk females (phenotype), and DNA analyses at seven linked marker loci. Linkage analysis based on restriction fragment length polymorphisms significantly improved risk estimates over those based on phenotype and pedigree alone. When all available information was combined, 85% (61/72) of the at-risk females had final risks of less than 5% or greater than 95%, and 68% (49/72) had risks less than 1% or greater than 99%. A diagnosis of hypohidrotic ectodermal dysplasia was also excluded (97.5% probability) by DNA and linkage analyses from a sample of cord blood from an at-risk male; a similar approach can be taken for prenatal diagnosis of the disorder.

Rapp-Hodgkin syndrome: an ectodermal dysplasia involving the teeth, hair, nails, and palate. Report of a case and review of the literature

Rapp-Hodgkin syndrome is a rare form of ectodermal dysplasia involving the hair, eyes, sweat glands, nails, teeth, and palate. The case of a white girl with the condition is presented. The differential diagnosis is discussed, and the eight previously reported cases are reviewed. Another (ninth) previously reported case is considered for inclusion in the group.

Mammographic screening for breast cancer: prospects for New Zealand

The Cancer Society and the Department of Health invited a working group to make recommendations on screening by mammography. Mammography offers the best opportunity for preventing deaths from breast cancer. Randomised trials suggest that mortality can be reduced by about 30% in women over 50; the value of routine mammography in younger women is still uncertain. Apart from financial costs, the main drawback of mammography is that many women receive unnecessary investigation because of false-positive results. Careful design and monitoring of programmes is essential to ensure that the benefits of screening outweigh the disadvantages. In New Zealand there is a shortage of radiologists, pathologists, and clinicians who are skilled in the specialised techniques required for the screening of asymptomatic women. Decisions about routine screening should be delayed until pilot programmes have been established, with assessment of their effectiveness, economic efficiency, and social acceptability. Recommendations for the design of such programmes are made.

X-linked hypohidrotic ectodermal dysplasia: localization within the region Xq11-21.1 by linkage analysis and implications for carrier detection and prenatal diagnosis

X-linked hypohidrotic ectodermal dysplasia (H.E.D.) is a disorder of abnormal morphogenesis of ectodermal structures and is of unknown pathogenesis. Neither relatively accurate carrier detection nor prenatal diagnosis has been available. Previous localization of the disorder by linkage analysis utilizing restriction-fragment polymorphisms, by our group and others, has placed the disorder in the general pericentromeric region. We have extended our previous study by analyzing 36 families by means of 10 DNA probes at nine marker loci and have localized the disorder to the region Xq11-Xq21.1, probably Xq12-Xq13. Three loci--DXS159 (theta = .01, z = 14.84), PGK1 (theta = .02, z = 13.44), and DXS72 (theta = .02, z = 11.38)--show very close linkage to the disorder, while five other pericentromeric loci (DXS146, DXS14, DXYS1, DXYS2, and DXS3) display significant but looser linkage. Analysis of the linkage data yields no significant evidence for nonallelic heterogeneity for the X-linked form of the disorder. Both multipoint analysis and examination of multiply informative meioses with known phase establish that the locus for H.E.D. is flanked on one side by the proximal long arm loci DXYS1, DXYS2, and DXS3 and on the other side by the short arm loci DXS146 and DXS14. Multipoint mapping could not resolve the order of H.E.D. and the three tightly linked loci. This order can be inferred from published data on physical mapping of marker loci in the pericentromeric region, which have utilized somatic cell hybrid lines established from a female with severe manifestations of H.E.D., and an X/9 translocation (breakpoint Xq13.1). If one assumes that the breakpoint of the translocation is within the locus for H.E.D. and that there has not been a rearrangement in the hybrid line, then DXS159 would be proximal to the disorder and PGK1 and DXS72 would be distal to the disorder. Both accurate carrier detection and prenatal diagnosis are now feasible in a majority of families at risk for the disorder.

Hypohidrotic ectodermal dysplasia

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Genetic control of susceptibility to atherosclerosis (with special emphasis on the role of the macrophage)

The pathogenesis of atherosclerosis involves a complex interplay of arterial endothelium, multiple cellular constituents, and circulating lipo/apolipoproteins. Early work implicated a single etiology--either excess of circulating lipids, disruption of endothelial integrity, or clonal proliferation of smooth muscle cells. However, current research supports a hypothesis unifying endothelial disruption with lipid imbibation. The macrophage is recognized as having an integral role in atherogenesis due to its capacity to adhere to endothelium, internalize and metabolize lipids, and liberate proteases, apolipoproteins, and mitogens. Genetically determined susceptibility or resistance to atherosclerosis has long been described in animals and man, and differences in lipo/apolipoproteins have been proposed to explain these variations. Genetically defined variants of inbred mice have been used to pursue hereditary influences in atherogenesis. Strain variations in lipid metabolism have been advanced as one possibility to explain a polygenic mode of inheritance--those strains most replete in cholesterol-enriched lipoproteins demonstrating the greatest susceptibility. However, there is now a substantial body of evidence suggesting that the diverse functions of the macrophage may be the mechanism underlying the genetic polymorphism in atherosclerosis. Recombinant inbred strains of mice may serve as a vehicle through which this concept can be explored.

Clinical aspects of X-linked hypohidrotic ectodermal dysplasia

Boys with X-linked hypohidrotic ectodermal dysplasia and their families were studied. Many suffered severe illness in early childhood and nearly 30% died; many had feeding problems, severe fever, atopic disease, and recurrent respiratory infections. Some infants failed to thrive. We found no consistent common endocrine or immunological abnormality, although, most had abnormal immunoglobulin production. This may be related to the abnormal mucosa of the gastrointestinal and respiratory tracts which exacerbates the chronic obstructive airways disease found later in life in those who smoke. Mental handicap was not a feature, although convulsions sometimes occurred during fever. Early diagnosis is important to avoid attacks of severe fever and so that rational management may be planned for other problems that arise. Dental advice should be sought before school age and genetic counselling may also be required. Many female carriers may be recognised at clinical examination: their affected sons can then be diagnosed more readily.

The hematologic effects of latamoxef sodium when used as a prophylaxis during surgical treatment

Latamoxef sodium, a third generation cephalosporin antibiotic, has been shown to provide good prophylaxis against postoperative infection. It has, however, been implicated as causing disturbances of hemostasis particularly when used in treatment. We have studied 40 patients who required antibiotic prophylaxis prior to surgical treatment randomizing and stratifying them according to age and type of operation, to receive either latamoxef or piperacillin. Five hematologic parameters were studied, prothrombin time, activated partial thromboplastin time, plasma factor II concentration, plasma factor VII concentration and platelet count. Minor differences were noted with latamoxef producing mild persistant elevation of prothrombin time (0.7 second) associated with depression of factor II and factor VII. In our study, we found that, when used as three dose, single agent prophylaxis, there was no difference between latamoxef and piperacillin in producing clinical disturbances of hemostasis. However, attention is drawn to the importance of recognizing that hemostatic disturbances can occur after the use of broad spectrum antibiotics as prophylaxis for surgical treatment Mechanisms of hemostatic disorders are reviewed and alternative hypotheses are suggested.

Outpatient evaluation of a rapid, direct test for detection of group A streptococci in throat swabs

A latex agglutination test (Marion Laboratories) was compared with standard culture methods for the detection of Group A streptococci in two studies of 500 throat swabs each. Swabs were first inoculated to sheep blood agar and then tested for Group A streptococcal antigen. The direct test performed with nearly identical sensitivity and specificity in the two phases of the study. Overall, Group A streptococci were isolated from 91 specimens, and 81 (89%) of these were detected by the direct latex test. The predictive value positive for the latex test was 90%, and the accuracy was 98%. The sensitivity of the latex test for detection of specimens having ten or more colonies of Group A streptococci was 95%. Non-Group A beta-hemolytic streptococci were isolated from 65 specimens, and all of these specimens had negative latex tests. The authors' findings suggest that this direct latex agglutination test is a reliable screening method for rapid detection of Group A streptococci in outpatient throat specimens.

X-linked hypohidrotic ectodermal dysplasia: DNA probe linkage analysis and gene localization

A linkage study of 24 families with hypohidrotic (anhidrotic) ectodermal dysplasia (HED) has been performed. The previously suggested linkage to DXYS1 has been confirmed, and linkage to probes DXS14 and DXS3 has been established. We suggest that the HED locus lies in the centromeric region between DXYS1 on the long arm and DXS14 on the short arm of the X chromosome, probably on proximal Xq.

Duchenne muscular dystrophy with adrenal insufficiency and glycerol kinase deficiency: high resolution cytogenetic analysis with molecular, biochemical, and clinical studies

A syndrome of Duchenne muscular dystrophy (DMD), adrenal hypoplasia, glycerol kinase deficiency, and mental retardation has been recognised. We report a further case ascertained from a history of DMD, severe mental retardation, and an Addison-like disorder. Cytogenetic analysis of the proband revealed an interstitial deletion of the short arm of the X chromosome. from Xp21.1 to Xp22.11, comprising about 9% of the length of the normal X chromosome. His mother was heterozygous for the deletion, but his maternal grandmother and sister both had two normal X chromosomes. DNA probe analysis confirmed the existence of a deletion in the affected boy, as probes 754, C7, XJ1-1, and pERT87 consistently failed to hybridize to his DNA. His sister was heterozygous for the RFLP associated with 754, thus confirming that she had two normal X chromosomes. There was no evidence of chronic granulomatous disease, other immunological defect, or retinitis pigmentosa in this case. Biochemical studies revealed gross glyceroluria and hyperglycerolaemia, indicating glycerol kinase deficiency which has been confirmed enzymatically. We have subsequently screened 21 other boys with DMD for glyceroluria and found one other case. Cytogenetic analysis has also been performed in nine other families, where a boy with DMD has been shown to have a deletion of DNA sequences localised to the region Xp21. None of these cases demonstrated any cytogenetic abnormality, nor has their clinical course been unusual.

Facilitating comprehension of discharge medication in elderly patients

Provision of adequate information is well established as an important determinant of patient compliance with taking medication. Elderly patients, who constitute a large proportion of patients discharged from hospital on medication, may be particularly at risk of unintentional noncompliance due to inadequate or forgotten information. This study demonstrates that counselling provided to the elderly by a clinical pharmacist significantly improved knowledge about medication and, therefore, the opportunity for compliance at home.

Duodenal delivery of levodopa for on-off fluctuations in parkinsonism: preliminary observations

The pathogenesis of on-off motor fluctuations in parkinsonism remains incompletely understood, but slowed or erratic gastric emptying of orally administered levodopa may be involved. In 3 patients with resistant on-off fluctuations, direct duodenal continuous infusion of levodopa via a nasoduodenal tube resulted in a heightened therapeutic effect, including a reduction in motor fluctuations. In 1 of these patients, continuous duodenal levodopa infusion produced greater benefit than did intermittent duodenal levodopa administration. Direct duodenal delivery of levodopa lessens the problems with gastric emptying and may be suitable for long-term therapy in selected patients with resistant on-off motor fluctuations.