749
POSITION ON BEING PUT DOWN AND ON WAKING. JANUARY-
OCTOBER, 1991
campaign in November, were practically identical in the two areas (table). No particular campaign had been conducted on the Isle of Man, a self-governing island between England, Scotland, and Wales. The national media had carried occasional features on SIDS and it may be that the sleeping position of babies may have been changing throughout the British Isles, even though no overt targeted campaign had taken place. It is therefore possible that the drop in SIDS rate in Scotland may have been a direct result of overall change in sleeping position. Institute of Child Health, Royal Hospital for Sick Children, Bristol BS2 8BJ. UK
Postgraduate Medical Centre, Douglas, Isle of Man 1.
JEAN GOLDING PETER FLEMING
STEPHANIE PARKES
Wigfield RE, Fleming PJ, Berry PJ, et al. Can the fall in Avon’s sudden infant death rate be explained by changes m sleeping position? Br Med J 1992; 304: 282-83.
Studying X inactivation SIR,-During early female mammalian embryogenesis one of the chromosomes in every cell becomes inactivated and remains inactive in the progeny of that cell. Ordinarily the number of cells with the paternally derived X and maternally derived X are roughly equal, but occasionally--either because the number of cells that are the anlage of an organ is very small or because cells with one or the other X that is active have a selective advantage-only cells with either the paternally or maternally derived X active may be represented in a tissue. When this happens, female heterozygotes fully express a sex-linked trait. Until a few years ago the determination of which X is active in a tissue depended on the use of X-linked polymorphisms. The most common of these, the glucose-6-phosphate dehydrogenase (G6PD) polymorphism, reached a useful frequency only among females of African ancestry. Differences in DNA sequences have been exploited, making use of the fact that methylation patterns differ between the active and inactive X,’ but this technique is difficult and is often sensitive enough to detect small cell populations. The discovery of a common polymorphism in cDNA nucleotide 1311 of the G6PD gene2,3 has afforded us an opportunity of determining which X chromosome is active in a tissue by polymerase chain amplification (PCR) of cDNA. Since mRNA is made only from the active X chromosome, this permits us to determine the ratio of activities of the X chromosomes in a tissue sample. The sensitivity of the proposed new method is high. As shown in the figure, artificial mixtures of amplified cDNA could detect the 1311T or 1311C product in ratios as low as 1:20. We have demonstrated the usefulness of this technique by studying a woman with X-linked chronic granulomatous disease (CGD), whose neutrophils failed to generate detectable levels of superoxide and were uniformly non-reactive in the nitrobluetetrazolium test. The patient was heterozygous at the G6PD nt 1311 locus. The father’s X chromosome had a T at G6PD nt 1311 and the mother was homozygous for the nt1311C. PCR-based amplification of cDNA prepared from the patient’s granulocytes revealed only the 1311T. We have identified this patient’s CGD mutation as a previously undescribed C-T substitution at nt 688, altering the arginine of aminoacid residue 226 to a stop codon. This mutation was present in neither the mother nor the father. These findings indicate that, within the limits of the sensitivity of this method, the patient’s granulocytes all utilised only one of her X chromosomes for mRNA production-namely, the one contributed by the father. Since the mutation is absent from the
two X
Allele-specific oligonucleotide hybridisation for G6PD nt 1311 polymorphism. Amplification of cDNA used sense primer nt 1232-1251 and antisense primer nt 1356-1375. Top: mixtures with indicated ratios prepared from male cDNA from subjects having the 1311 C and 1311T genotypes. Middle. amplification of cDNA from two female heterozygous controls (1 and 2) and from propositus (3) Bottom amplification of genomic DNA.2 Female heterozygous controls (1 and 2); propositus (3); father of propositus (4), mother of propositus (5)
father’s somatic cells, it must represent a new mutation in the paternal germ line. 20-50% of women of all races are heterozygous for the nt1311 polymorphism so it should prove a powerful means for studying the clonal origin of tissues and disease. Department of Molecular and
Experimental Medicine,
Scripps Research Institute, La Jolla, Caifornia, USA
JOHN T. CURNUTTE PENELOPE J. HOPKINS WANDA KUHL ERNEST BEUTLER
1. Fearon ER, Hamilton SR, Vogelstein B. Clonal analysis of human colorectal tumors. Science 1987; 238: 192-97. 2. Beutler E, Kuhl W. The NT 1311 polymorphism of G6PD: G6PD Mediterranean mutation may have originated independently in Europe and Asia. Am J Hum Genet
1990; 47: 1008-1012. B, Mason PJ, Berrebi A, et al. Origin and spread of the glucose-6phosphate dehydrogenase variant (G6PD-Mediterranean) in the Middle East. Am J Hum Genet 1990; 47: 1013-19.
3. Kurdi-Haidar
Illness behaviour after common whiplash SIR- There is disagreement about whether symptoms persisting beyond six months are directly attributable to whiplash injury.! In the absence of identifiable somatic correlates (eg, neurological or scan findings) complaints continuing after whiplash injury tend to be thought of in terms of neurosisz or malingering.3 However, symptoms after whiplash are fairly uniform, and their accurate simulation by all victims is inconceivable. Laypersons tend to assume that severe injury is necessary to produce whiplash symptoms.’ However, the relation between the patient’s familiarity with whiplash symptoms and the outcome has yet to be investigated. Symptom familiarity apart, factors that may influence outcome are the patient’s assessment of the accident (eg, trivial vs serious, and thus potentially leading to an unfavourable outcome); the initial emotional reaction; the timing of the onset of symptoms; the initial concern about long-lasting illness or disability; and
750
FACTORS, AS ASSESSED AT FIRST INTERVIEW, IN THOSE WITHOUT AND WITH SYMPTOMS AT SIX MONTHS
*In
no
disease and Marmot and Poulter’s recommendations should be regarded as applicable to men and women in all age groups, including both elderly (patients aged 60-75) and those over 75 years.
patient was post-traumatic stress disorder diagnosed.
neurological symptoms, especially
when there is
experience of
in close relatives. We have assessed these factors in a random sample of 109 recent whiplash injuries. All patients (mean age 31 years [SD = 10]; 66 women, 43 men) had been injured in automobile accidents and were fully covered by insurance.! Patients were selected according to a definition of common whiplash 5which excludes head injury or traumatic alteration of consciousness. Patients were questioned as soon as possible after trauma (mean 73 days [4-2]) and again 6 months later. At the first interview the factors were assessed and at 6 months the sample was divided into a symptom-free group (n 72) and a group with symptoms (n 37). There were no significant differences between the two groups in respect of any of the factors (table). All patients were fully covered by insurance so biases due to compensation-seeking behaviour will not have been important in this sample. These findings do not support the suggestion3that illness behaviour of whiplash patients is primarily attributable to factors unrelated to injury. trauma
=
=
Departments of Psychiatry and Neurology, University of Berne, CH-3010 Berne, Switzerland 1.
excess risk falls to two-fold after adjustment for age, cigarette smoking, and blood pressure, but remains significant. Ina further report on these men, we have shown that physical activity is inversely associated with the risk of stroke independent of coronary risk factors, heavy drinking, and pre-existing ischaernic heart disease or strokeModerate activity is associated with a 40% reduction in risk of stroke relative to inactive men, and vigorous activity with a 70% reduction in risk. Stroke is probably more readily preventable than ischaemic heart
stroke. This
BOGDAN P. RADANOV AYESHA SCHNIDRIG GIUSEPPE DI STEFANO MATTHIAS STURZENEGGER
Pearce JMS. Whiplash injury: a reappraisal. J Neurol Neurosurg Psychiatry 1989; 52:
1329-31. 2. Hodge JR. The whiplash neurosis Psychosomatics 1971; 12: 245-49. 3. Mills H, Home G. Whiplash: manmade disease? NZ Med J 1986; 99: 373-74. 4. Aubrey JB, Dobbs AR, Rule BG. Laypersons’ knowledge about the sequelae of minor head injury and whiplash. J Neurol Neurosurg Psychiatry 1989; 52: 842-46. 5. Radanov BP, Di Stefano G, Schnidrig A, Ballinari P. Role of psychosocial stress m recovery from common whiplash. Lancet 1991, 338: 712-15.
Department of Public Health and Primary Care, Royal Free Hospital School of Medicine,
A. G. SHAPER
London NW3 2PF, UK
Pocock SJ, Walker M, Macfarlane PW. Risk factors for stroke in middle-aged British men. Br MedJ 1991; 302: 1111-15. 2. Wannamethee G, Shaper AG. Physical activity and stroke in British middle-aged men. Br MedJ (in press). 1.
Shaper AG, Phillips AN,
SIR,-During the Stroke Octet (Opus 2) Professor Marmot and Dr Poulter indicate that the importance of overweight in causing stroke may have been previously underestimated. The Whitehall study analysis to which they refer suggested three, rather than one, possible explanations for this.’ As Marmot and Poulter mention, controlling the risks of overweight for mechanisms through which excessive body fat may increase risk is inappropriate. Diabetes mellitus, hypertension, and hypercholesterolaemia are almost certainly causally related to overweight. Second, a positive linear association between body mass index and stroke death was seen in those reporting never smoking cigarettes but not in current and former smokers-in whom the relation more resembled a U-shape. Third, the positive linear association between body mass index and stroke death seen in younger subjects (40-54 years) changed to a U-shaped relation in the older group (55-64). This, perhaps, was because some older subjects had weight loss associated with illnesses that also increased their risk of stroke. Studies addressing the causal role of overweight in stroke might well benefit from concentrating on never smokers and lifelong peak values for body fat. Department of Medicine, Walsgrave Hospital, Coventry CV2 2DX, UK 1. Shinton
Stroke SIR,-Professor Marmot and Dr Poulter’s article on primary prevention of stroke (Feb 8, p 344) draws attention to the importance of blood pressure and cigarette smoking but does not
emphasise the considerable synergism that occurs when these risk are present concurrently. The table indicates the individual importance of both systolic blood pressure and current cigarette smoking in the risk of stroke and emphasises the striking multiplicative effect of their interaction in middle-aged British men (the British Regional Heart Study).1 In this study, ex-smokers had the same risk of stroke as those who had never smoked, suggesting that giving up smoking may be almost the most important action a hypertensive subject can take to reduce the risk of stroke. The same study makes it clear that, in men initially free of a previous cardiovascular disease (ischaemic heart disease, stroke, hypertension), heavy drinking (more than 6 drinks daily) is associated with a nearly four-fold increase in the relative risk of factors
RELATIVE RISK OF STROKE IN MEN ACCORDING TO SYSTOLIC BLOOD PRESSURE AND SMOKING STATUS
*Figures m parentheses are number of strokes/number of men
R, Shipley M, Rose G. Overweight and J Epidemiol Commun Health 1991; 45: 138-42.
ROGER SHINTON stroke in the Whitehall
Study.
SIR,-In any discussion of the aetiology of stroke (Dr Bonita, Feb 8, p 342), with regret one must now include the importance of the vasospastic activity of misused psychostimulant drugs, especially cocaine. It is the impression of our emergency room staff that between one in five and one in ten admissions for assessment of cerebrovascular occlusive disease is directly or indirectly associated with such misuse. Addiction Rehabilitation Program, Bellevue Hospital Center, New York, New York 10016, USA
ROBERT MASLANSKY
Measles virus antibody in aqueous humour of patients with uveitis associated with
multiple sclerosis SIR,-Myelin loss is a key element in brain lesions of multiple sclerosis (MS). Measles virus may have a role as a triggering factor or even an aetiological agent (see Waksman’s review’) and various studies have prompted the hypothesis that an immunological reaction against measles virus could destroy myelin, there being peptide sequences common to viral antigens and myelinic proteins.2,3 MS may have ocular manifestations,’ and intraocular inflammation, notably of the intermediate and posterior uvea, occurs in 18-20% of patients,5,6 though symptoms of uveitis develop in only 1-5%." The presence of inflammation suggests that there might in MS be forms of immunological conflict in the central
POSITION ON BEING PUT DOWN AND ON WAKING. JANUARY-
OCTOBER, 1991
campaign in November, were practically identical in the two areas (table). No particular campaign had been conducted on the Isle of Man, a self-governing island between England, Scotland, and Wales. The national media had carried occasional features on SIDS and it may be that the sleeping position of babies may have been changing throughout the British Isles, even though no overt targeted campaign had taken place. It is therefore possible that the drop in SIDS rate in Scotland may have been a direct result of overall change in sleeping position. Institute of Child Health, Royal Hospital for Sick Children, Bristol BS2 8BJ. UK
Postgraduate Medical Centre, Douglas, Isle of Man 1.
JEAN GOLDING PETER FLEMING
STEPHANIE PARKES
Wigfield RE, Fleming PJ, Berry PJ, et al. Can the fall in Avon’s sudden infant death rate be explained by changes m sleeping position? Br Med J 1992; 304: 282-83.
Studying X inactivation SIR,-During early female mammalian embryogenesis one of the chromosomes in every cell becomes inactivated and remains inactive in the progeny of that cell. Ordinarily the number of cells with the paternally derived X and maternally derived X are roughly equal, but occasionally--either because the number of cells that are the anlage of an organ is very small or because cells with one or the other X that is active have a selective advantage-only cells with either the paternally or maternally derived X active may be represented in a tissue. When this happens, female heterozygotes fully express a sex-linked trait. Until a few years ago the determination of which X is active in a tissue depended on the use of X-linked polymorphisms. The most common of these, the glucose-6-phosphate dehydrogenase (G6PD) polymorphism, reached a useful frequency only among females of African ancestry. Differences in DNA sequences have been exploited, making use of the fact that methylation patterns differ between the active and inactive X,’ but this technique is difficult and is often sensitive enough to detect small cell populations. The discovery of a common polymorphism in cDNA nucleotide 1311 of the G6PD gene2,3 has afforded us an opportunity of determining which X chromosome is active in a tissue by polymerase chain amplification (PCR) of cDNA. Since mRNA is made only from the active X chromosome, this permits us to determine the ratio of activities of the X chromosomes in a tissue sample. The sensitivity of the proposed new method is high. As shown in the figure, artificial mixtures of amplified cDNA could detect the 1311T or 1311C product in ratios as low as 1:20. We have demonstrated the usefulness of this technique by studying a woman with X-linked chronic granulomatous disease (CGD), whose neutrophils failed to generate detectable levels of superoxide and were uniformly non-reactive in the nitrobluetetrazolium test. The patient was heterozygous at the G6PD nt 1311 locus. The father’s X chromosome had a T at G6PD nt 1311 and the mother was homozygous for the nt1311C. PCR-based amplification of cDNA prepared from the patient’s granulocytes revealed only the 1311T. We have identified this patient’s CGD mutation as a previously undescribed C-T substitution at nt 688, altering the arginine of aminoacid residue 226 to a stop codon. This mutation was present in neither the mother nor the father. These findings indicate that, within the limits of the sensitivity of this method, the patient’s granulocytes all utilised only one of her X chromosomes for mRNA production-namely, the one contributed by the father. Since the mutation is absent from the
two X
Allele-specific oligonucleotide hybridisation for G6PD nt 1311 polymorphism. Amplification of cDNA used sense primer nt 1232-1251 and antisense primer nt 1356-1375. Top: mixtures with indicated ratios prepared from male cDNA from subjects having the 1311 C and 1311T genotypes. Middle. amplification of cDNA from two female heterozygous controls (1 and 2) and from propositus (3) Bottom amplification of genomic DNA.2 Female heterozygous controls (1 and 2); propositus (3); father of propositus (4), mother of propositus (5)
father’s somatic cells, it must represent a new mutation in the paternal germ line. 20-50% of women of all races are heterozygous for the nt1311 polymorphism so it should prove a powerful means for studying the clonal origin of tissues and disease. Department of Molecular and
Experimental Medicine,
Scripps Research Institute, La Jolla, Caifornia, USA
JOHN T. CURNUTTE PENELOPE J. HOPKINS WANDA KUHL ERNEST BEUTLER
1. Fearon ER, Hamilton SR, Vogelstein B. Clonal analysis of human colorectal tumors. Science 1987; 238: 192-97. 2. Beutler E, Kuhl W. The NT 1311 polymorphism of G6PD: G6PD Mediterranean mutation may have originated independently in Europe and Asia. Am J Hum Genet
1990; 47: 1008-1012. B, Mason PJ, Berrebi A, et al. Origin and spread of the glucose-6phosphate dehydrogenase variant (G6PD-Mediterranean) in the Middle East. Am J Hum Genet 1990; 47: 1013-19.
3. Kurdi-Haidar
Illness behaviour after common whiplash SIR- There is disagreement about whether symptoms persisting beyond six months are directly attributable to whiplash injury.! In the absence of identifiable somatic correlates (eg, neurological or scan findings) complaints continuing after whiplash injury tend to be thought of in terms of neurosisz or malingering.3 However, symptoms after whiplash are fairly uniform, and their accurate simulation by all victims is inconceivable. Laypersons tend to assume that severe injury is necessary to produce whiplash symptoms.’ However, the relation between the patient’s familiarity with whiplash symptoms and the outcome has yet to be investigated. Symptom familiarity apart, factors that may influence outcome are the patient’s assessment of the accident (eg, trivial vs serious, and thus potentially leading to an unfavourable outcome); the initial emotional reaction; the timing of the onset of symptoms; the initial concern about long-lasting illness or disability; and
750
FACTORS, AS ASSESSED AT FIRST INTERVIEW, IN THOSE WITHOUT AND WITH SYMPTOMS AT SIX MONTHS
*In
no
disease and Marmot and Poulter’s recommendations should be regarded as applicable to men and women in all age groups, including both elderly (patients aged 60-75) and those over 75 years.
patient was post-traumatic stress disorder diagnosed.
neurological symptoms, especially
when there is
experience of
in close relatives. We have assessed these factors in a random sample of 109 recent whiplash injuries. All patients (mean age 31 years [SD = 10]; 66 women, 43 men) had been injured in automobile accidents and were fully covered by insurance.! Patients were selected according to a definition of common whiplash 5which excludes head injury or traumatic alteration of consciousness. Patients were questioned as soon as possible after trauma (mean 73 days [4-2]) and again 6 months later. At the first interview the factors were assessed and at 6 months the sample was divided into a symptom-free group (n 72) and a group with symptoms (n 37). There were no significant differences between the two groups in respect of any of the factors (table). All patients were fully covered by insurance so biases due to compensation-seeking behaviour will not have been important in this sample. These findings do not support the suggestion3that illness behaviour of whiplash patients is primarily attributable to factors unrelated to injury. trauma
=
=
Departments of Psychiatry and Neurology, University of Berne, CH-3010 Berne, Switzerland 1.
excess risk falls to two-fold after adjustment for age, cigarette smoking, and blood pressure, but remains significant. Ina further report on these men, we have shown that physical activity is inversely associated with the risk of stroke independent of coronary risk factors, heavy drinking, and pre-existing ischaernic heart disease or strokeModerate activity is associated with a 40% reduction in risk of stroke relative to inactive men, and vigorous activity with a 70% reduction in risk. Stroke is probably more readily preventable than ischaemic heart
stroke. This
BOGDAN P. RADANOV AYESHA SCHNIDRIG GIUSEPPE DI STEFANO MATTHIAS STURZENEGGER
Pearce JMS. Whiplash injury: a reappraisal. J Neurol Neurosurg Psychiatry 1989; 52:
1329-31. 2. Hodge JR. The whiplash neurosis Psychosomatics 1971; 12: 245-49. 3. Mills H, Home G. Whiplash: manmade disease? NZ Med J 1986; 99: 373-74. 4. Aubrey JB, Dobbs AR, Rule BG. Laypersons’ knowledge about the sequelae of minor head injury and whiplash. J Neurol Neurosurg Psychiatry 1989; 52: 842-46. 5. Radanov BP, Di Stefano G, Schnidrig A, Ballinari P. Role of psychosocial stress m recovery from common whiplash. Lancet 1991, 338: 712-15.
Department of Public Health and Primary Care, Royal Free Hospital School of Medicine,
A. G. SHAPER
London NW3 2PF, UK
Pocock SJ, Walker M, Macfarlane PW. Risk factors for stroke in middle-aged British men. Br MedJ 1991; 302: 1111-15. 2. Wannamethee G, Shaper AG. Physical activity and stroke in British middle-aged men. Br MedJ (in press). 1.
Shaper AG, Phillips AN,
SIR,-During the Stroke Octet (Opus 2) Professor Marmot and Dr Poulter indicate that the importance of overweight in causing stroke may have been previously underestimated. The Whitehall study analysis to which they refer suggested three, rather than one, possible explanations for this.’ As Marmot and Poulter mention, controlling the risks of overweight for mechanisms through which excessive body fat may increase risk is inappropriate. Diabetes mellitus, hypertension, and hypercholesterolaemia are almost certainly causally related to overweight. Second, a positive linear association between body mass index and stroke death was seen in those reporting never smoking cigarettes but not in current and former smokers-in whom the relation more resembled a U-shape. Third, the positive linear association between body mass index and stroke death seen in younger subjects (40-54 years) changed to a U-shaped relation in the older group (55-64). This, perhaps, was because some older subjects had weight loss associated with illnesses that also increased their risk of stroke. Studies addressing the causal role of overweight in stroke might well benefit from concentrating on never smokers and lifelong peak values for body fat. Department of Medicine, Walsgrave Hospital, Coventry CV2 2DX, UK 1. Shinton
Stroke SIR,-Professor Marmot and Dr Poulter’s article on primary prevention of stroke (Feb 8, p 344) draws attention to the importance of blood pressure and cigarette smoking but does not
emphasise the considerable synergism that occurs when these risk are present concurrently. The table indicates the individual importance of both systolic blood pressure and current cigarette smoking in the risk of stroke and emphasises the striking multiplicative effect of their interaction in middle-aged British men (the British Regional Heart Study).1 In this study, ex-smokers had the same risk of stroke as those who had never smoked, suggesting that giving up smoking may be almost the most important action a hypertensive subject can take to reduce the risk of stroke. The same study makes it clear that, in men initially free of a previous cardiovascular disease (ischaemic heart disease, stroke, hypertension), heavy drinking (more than 6 drinks daily) is associated with a nearly four-fold increase in the relative risk of factors
RELATIVE RISK OF STROKE IN MEN ACCORDING TO SYSTOLIC BLOOD PRESSURE AND SMOKING STATUS
*Figures m parentheses are number of strokes/number of men
R, Shipley M, Rose G. Overweight and J Epidemiol Commun Health 1991; 45: 138-42.
ROGER SHINTON stroke in the Whitehall
Study.
SIR,-In any discussion of the aetiology of stroke (Dr Bonita, Feb 8, p 342), with regret one must now include the importance of the vasospastic activity of misused psychostimulant drugs, especially cocaine. It is the impression of our emergency room staff that between one in five and one in ten admissions for assessment of cerebrovascular occlusive disease is directly or indirectly associated with such misuse. Addiction Rehabilitation Program, Bellevue Hospital Center, New York, New York 10016, USA
ROBERT MASLANSKY
Measles virus antibody in aqueous humour of patients with uveitis associated with
multiple sclerosis SIR,-Myelin loss is a key element in brain lesions of multiple sclerosis (MS). Measles virus may have a role as a triggering factor or even an aetiological agent (see Waksman’s review’) and various studies have prompted the hypothesis that an immunological reaction against measles virus could destroy myelin, there being peptide sequences common to viral antigens and myelinic proteins.2,3 MS may have ocular manifestations,’ and intraocular inflammation, notably of the intermediate and posterior uvea, occurs in 18-20% of patients,5,6 though symptoms of uveitis develop in only 1-5%." The presence of inflammation suggests that there might in MS be forms of immunological conflict in the central
