BMJ
2001;323:1035-1036 ( 3 November )
Kate Bushby
a Institute of Human Genetics,
International Centre for Life, Newcastle upon Tyne NE1 3BZ, b Centre
for Urban and Regional Development Studies, University of Newcastle upon Tyne,
Newcastle upon Tyne NE1 7RU, c Medical School, University of
Newcastle upon Tyne, Newcastle upon Tyne NE2 4BW, d Department
of Restorative Dentistry, University of Newcastle upon Tyne, Newcastle upon
Tyne NE2 4BW
Correspondence to: K Bushby [log in to unmask]
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Participants,
methods, and results |
Records of children with Duchenne muscular dystrophy in the
Northern region of England have been scrupulously maintained since the
1960s, and we believe that ascertainment in the region is complete.
We analysed data from the whole group of families with Duchenne
muscular dystrophy in the region and also subdivided the group into
four categories according to the origin of the mutation in the
family (table).
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In all, 229 of the 246 families with children diagnosed
as having Duchenne muscular dystrophy between 1967 and 1999 in the
Northern region had valid postcodes available at diagnosis. We linked
patients' postcodes to data from the latest national census by using
the central postcode directory, which provides a link between
postcodes and enumeration districts consisting of 100-150 households.
No enumeration district contained more than one affected family, and
each family was counted as a single case irrespective of the number
of boys affected.
We used a non-parametric test (Mann-Whitney U test) to compare the
Townsend scores2
for enumeration districts in which cases of Duchenne muscular dystrophy
occurred against all enumeration districts in the region without
cases, for all cases and for the four subgroups. We then used Monte
Carlo analysis to compare the mean and distribution of scores for
the enumeration districts of all affected families with the
distribution of Townsend scores derived from repeated random samples
of enumeration districts.
The results (table) show large and significant differences between
the Townsend scores of affected families and Townsend score distributions
for the rest of the population (corrected for the number of children
aged 5 and under). The differences occurred in all of the
subgroups. The Monte Carlo analysis confirmed the difference between
affected families and the rest of the populationthe mean Townsend score for the affected boys was at
least 2.5 standard deviations greater than that for the random
control groups in every iteration.
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Comment |
As a group, patients with Duchenne muscular dystrophy have
significantly greater material deprivation at diagnosis than the average
of the population from which they are drawn. This is evident even in
families where the disease is known to be the result of a new
mutation. We can find no simple explanation for this effect, but it
seems that new mutations in the dystrophin gene do not occur
randomly in the population. The rate of new germline mutations in
the dystrophin gene is particularly high,1 and the
mechanisms by which these mutations occur are poorly understood.
Further studies are needed to determine what aspects or covariates
of deprivation may contribute to this effect and whether this
ecological association occurs for other genes with a high level of
new mutations.
Patients from deprived backgrounds have less access to health care
than people from more affluent areas, 3 4 and
diagnosis of Duchenne muscular dystrophy is often delayed.5 Children
with Duchenne muscular dystrophy have a lifelong need for the highest
quality of care, and the relatively high levels of deprivation associated
with the disease may restrict availability of the sustained, high
quality, specialised support needed.
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Acknowledgments |
Angela Hill provided much of the
inspiration for this work. We thank Dr Louise Parker for helpful comments.
Contributors: KB oversaw the project and cowrote the paper. She is
the guarantor. SR analysed the data. SO'D collected and processed the data. JGS
contributed to developing the hypothesis and cowrote the paper.
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Footnotes |
Funding: The Newcastle Muscle Centre receives financial support
from the Muscular Dystrophy Campaign.
Competing interests: None declared.
Further details of methods are on the BMJ's website
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References |
1. |
Gorospe JR, Hoffman EP. Duchenne
muscular dystrophy. Curr Opin Rheumatol
1992; 4: 794-800 |
2. |
Townsend P, Phillimore P, Beattie A. Health and deprivation: inequality and the north.
London: Croom Helm, 1988 |
3. |
Benzeval M, Judge K. Access to healthcare
in England: continuing inequalities in the distribution of general
practitioners. J Pub Health Med
1996; 18: 33-40 |
4. |
Acheson D. Independent enquiry into inequalities in health. London:
Stationery Office, 1998. |
5. |
Bushby K, Hill A, Steele JG. Failure of
early diagnosis in symptomatic Duchenne muscular dystrophy. Lancet 1999; 353: 557-558 |
(Accepted 11 July 2001)
Edward E.
Rylander, M.D.
Diplomat American
Board of Family Practice.
Diplomat American
Board of Palliative Medicine.