Chapter 2: Duchenne Muscular Dystrophy: A clinical overview
Due to its physical, emotional and social complexities there are many ways to describe DMD. This chapter offers a guide to the scientific discoveries that inform current biomedical knowledge about the genetic condition, Duchenne muscular dystrophy (DMD). The research I address here speaks, in some ways, to Fassin’s careful analysis of the different measures of the value, or worth, of lives. The focus in this chapter is the biomedical understanding of DMD and is based within the frame of the medical gaze (Foucault 1973). Using this frame Foucault noted a development that occurred during the eighteenth and nineteenth centuries in which the human body came to be studied in isolation from its personality and social circumstances. While this approach is a well acknowledged phenomenon of modernity (Foucault 1973: xii-xiii), Foucault focusses on its epistemological significance and describes a shift in authority. As the medical gaze came to dominate an understanding of human health, greater authority was attributed to biomedical knowledge. This biomedical way of understanding DMD is central for the DMD community with whom I conducted my research and is one of the fundamental principles underlying the provision of services. Current biomedical knowledge about DMD is the result of the detailed observations and investigations of physicians and scientists over the past two centuries. Each discovery has added another piece to the complex puzzle that is DMD. This history informs the way DMD is treated, as knowledge is applied to treatment, and these enactments (following Mol 2002) contribute to a constant refinement of what DMD is. Furthermore they reiterate the way in which lives are valued in biological, rather than political terms (Fassin 2012:112).
Today those involved with DMD know that it is a distinct condition within a range of physiologically similar muscular dystrophies. There is a thorough understanding of molecular biology which informs the genetic nature of the muscular dystrophies and the processes whereby genetic mutations occur. The gene that is responsible for DMD and the protein this gene codes for has been discovered. Scientists and others in the DMD community know a great deal about the function of this protein and doctors know how best to treat DMD with existing therapies. The piece of the puzzle that families are waiting for is the piece that will offer patients longevity and mobility. This overview emphasises the crucial importance of this biomedical epistemology, the repeatable research outcomes that contribute to the clinical understanding and medical treatment of DMD. This particular epistemology is imbued by the DMD community with hope. It is through biomedical research and expertise that the families maintain the hope for a future effective treatment for this devastating condition.
The following clinical history can be described as a Foucauldian archaeology of the knowledge of DMD. O’Farrell (2005:68) acknowledges that it is difficult to distinguish between the way Foucault uses ideas about an archaeology of knowledge and his ideas about genealogy. But as this chapter is a history of knowledge, rather than a consideration of the power inherent in this knowledge, it seems to be more archaeological than genealogical (O’Farrell 2005:69). Here I describe how research findings follow on from each other and how knowledge about DMD is cumulative. Foucault contends that illness is a disorder (Foucault 1973) and that science attempts to create order or understanding by imposing logical, systematic categories of knowledge into which different diseases and different aspects of disease fit. This is reflected in this account of DMD. I trace a history of scientific development and in later chapters consider some the ways this knowledge is used to condition and control people’s subjectivities
What is Duchenne Muscular Dystrophy (DMD)?
Duchenne muscular dystrophy is a severe form of muscular dystrophy. It occurs as a result of mutations in the dystrophin gene, DMD locus Xp21.2. DMD generally occurs in boys and can be inherited. It is an x-linked recessive genetic condition. The DMD gene is the largest human gene and it codes for the protein dystrophin. When there is a mutation in this gene the human body is unable to produce the muscle protein dystrophin and a loss of muscle function and weakness occurs.
Duchenne muscular dystrophy affects approximately 1:3,500 male births worldwide. DMD occurs both through familial inheritance and through spontaneous mutations of the Duchenne gene. Approximately 2/3 of cases are inherited. In all hereditary cases the mother carries the faulty gene and passes it to her affected son(s). I have not heard of a case where a father has passed his faulty gene to a daughter. The degenerative nature of the disease and the premature death associated with it makes this scenario unlikely. If treatment improves it is possible men with DMD may pass the faulty gene to their daughters in the usual way X linked recessive inheritance occurs (Muscular Dystrophy Association, 2016a).
What are the Symptoms of DMD?
While the age of onset and the rate of deterioration can vary, DMD is a highly predictable condition. I have used information from the website of National Genome Institute and the website of the New Zealand Muscular Dystrophy Association to write this summary but there are many, many other similar sources that refer to this same pattern of symptoms. Initial indicators are usually noticed before the age of six and may appear in early infancy. Typically the first noticeable symptom is a delay of motor milestones, including sitting and standing independently. Usually boys do not walk until eighteen months. The muscles of the legs and pelvis waste and weaken. This can lead to a distinctive waddling gait, difficulty in climbing upstairs and a distinctive way of standing up called a Gower’s manoeuvre. Frequent falls are also a feature of this condition. The muscles of the arms, neck and other areas also weaken, but not as severely or as early as those in the lower half of the body.
Boys with muscular dystrophy often appear to have large calf muscles in their early years. However the muscle tissue is replaced with fat and connective tissue. Calves may look large and strong but in fact there is no muscle strength. Associated muscle contracture causes joint problems, first in the ankles, followed by the knees, hips and joints of the upper body. Between the ages of one and six a person with DMD will in all likelihood have manifested some symptoms. Muscle strength steadily declines between the ages of six and eleven. By the age of ten braces may be required for walking and by age twelve, most boys are using wheelchairs.
Bones may be malformed and curvature of the spine can result. Curvature of the spine (scoliosis) is a serious problem in DMD. Scoliosis is a curvature to the side, accompanied by rotation of the spine. Scoliosis worsens most rapidly in the latter stages of puberty, during the growth spurt. If severe, scoliosis can be extremely uncomfortable, and limits the function of the lungs and the upper limbs. It is also disfiguring, causing the chest wall to become more prominent on one side.
In the later stages of DMD breathing difficulties occur. This can be due to both deterioration of the diaphragm and curvature of the spine. Cardiomyopathy (enlarged heart) occurs in many cases and for some this will have commenced during the early teens. Sometimes mild intellectual impairment is associated with DMD but it does not worsen over time, as the other symptoms do. Intellectual impairment occurs in 35% of DMD cases. It is uncommon for people to live beyond 30 years, although longevity is currently increasing as treatments and management regimens improve.
History of DMD
first case of a condition with the symptoms of muscular dystrophy, recorded in English, dates from 1830. Charles Bell, surgeon, describes a case study in his book The Nervous System of the Human Body. The symptoms Bell describes seem likely to be a case of muscular dystrophy. Bell did not undertake muscle pathology so the case is a probable, rather than definite, description of muscular dystrophy. As the patient was able to climb stairs at the age of eighteen, it is also likely that the case was Becker muscular dystrophy (BMD) not DMD (Emery and Emery 2011:18).
In 1836 an Italian physician reported brothers with probable symptoms. Professor Gaetano Conte was Head of Department at the Hospital for Incurables in Naples. He describes two brothers whose symptoms included; hypertrophy of the calf and deltoid muscles, progressive muscle weakness that began in the legs, the elder brother died at age seventeen from suspected hypertrophy of the heart, the younger brother suffered from severe joint contractures and an enlarged tongue. Again no muscle pathology was undertaken so the diagnosis cannot be certain. Nevertheless, as Emery and Emery point out “this appears to be the very first detailed clinical description of muscular dystrophy” (2011:20).
By 1847 autopsy results for a fourteen year old boy who probably had DMD were presented to the Pathological Society of London. Richard Partridge, a respected anatomist and teacher (Emery and Emery 2011:21), undertook muscle examination during an autopsy on the boy. The boy had from the age of 9 developed a progressive muscle wasting condition with the large calf muscles and contractures associated with DMD. He had died from pneumonia after catching measles. Partridge noted that the distinctive fatty nature of the calf muscles. Partridge’s autopsy involved the macroscopic study of muscle tissue but not microscopic study. Microscopic study of muscle tissue was undertaken by William J Little, a senior physician at The Royal Orthopaedic Hospital, London, with a particular interest in “deformities”. Little’s findings (1853) almost certainly suggest that the boy suffered from DMD. Little notes, “The degenerated muscles exhibited abundance of fat cells, with few traces of muscular fibre; in some fibrillae the transverse markings were scarcely distinguishable, in others they were quite distinct” (in Emery and Emery 2011:24).
British physician Edward Meryon is, according to the account of Emery and Emery, the first doctor to distinguish the common traits of DMD, “…it was Meryon’s great contribution to realize the similarity among the various cases and, most significantly, that they represented a specific and unique disease entity” (Emery and Emery 2011:35).
In 1851 he presented his findings about the similarities of a muscle wasting condition in nine boys, brothers in three separate families. His discussion included reference to the microscopic analysis of muscle tissue, and the spinal cord during an autopsy procedure. Emery and Emery (2011:36) note that at this time technological advances increased the use of microscopic study by medical investigators. Meryon also published articles about this condition in 1866 and 1870 with data that indicated the condition occurred in siblings, predominantly brothers and with recognition that it might be inherited maternally.
Although Meryon noticed a common familial pattern to the condition he was not precisely aware of the hereditary pathway of the disease. Heredity was not well understood in the mid-1800s. Mendel’s work on inheritance, published in 1865, was not widely disseminated until 1900. Clues to the way this condition is transmitted did exist in the mid nineteenth century. It has the same mode of transmission as haemophilia (another X-linked recessive genetic condition) and this was well-known. In fact, the hereditary pathway of haemophilia is recognised in the Talmud, which excuses at risk male babies from circumcision.
In 1861 Guillaume B. A. Duchenne (1806-1875), a French GP, refers in one of his publications to a patient he first treated in 1858 with clinical symptoms of DMD. In this publication the case is only briefly described and no histological (microscopic tissue study) findings are mentioned. However, Duchenne encounters other similar cases and in 1868 he published, “… an extensive series of articles” (Emery and Emery 2011:82). These articles include his original patient and twelve additional cases. Duchenne also reviewed fifteen German cases reported in German medical journals. Duchenne identified the stages of the progress of the disease.
One of his major contributions to understanding the condition came from his interest in muscle pathology. Duchenne invented a tool for obtaining muscle tissue from patients. This allowed him to make observation on the muscle tissue without requiring a body to be available for autopsy. The most fundamental abnormality in the muscle tissue that he noted under microscopic investigation was the hyperplasia (enlargement due to an increase in cells) of the fibrous connective tissue, which later turned into fatty tissue. Duchenne was unable to explain how this increase in connective tissue occurred. His detailed clinical descriptions and thorough pathological analysis were an important steppingstone in the understanding of the complexities of the disease. Duchenne, however, did not note the familial traits of the disease.
Meryon and Duchenne were doctors practising in similarly large industrial cities during the same medically stimulating times. They identified the clinical parameters of DMD and made some initial steps in discovering its pathology however there was still an enormous amount of research to be undertaken to clarify the nature of the disease.
Chapter 1: How are Lives with DMD Valued in Aotearoa New Zealand?
Thesis Question and Overview
Debates in Disability
Concepts of Resilience, Hope and Value
Governmentality, Biopower and the Anthropology of Policy
Examining the Relationships within DMD Networks
Local Biologies and the Discourse of Biomedicine
Chapter 2: Duchenne Muscular Dystrophy: A clinical overview
What is Duchenne Muscular Dystrophy (DMD)?
What are the Symptoms of DMD?
History of DMD
Classification within the Muscular Dystrophies
Further Significant Discoveries
Isolation of the Duchenne Gene40
Chapter 3: Research Design and Methods
Construction of the Field
Co-production of Knowledge
Ethical Dilemmas: Emotional Intensity and Anonymity
Researcher Empathy and Subjectivity
Chapter 4: Rationales for New Zealand’s Health and Disability Provisions
Funding: Ministry of Health and Accident Compensation Corporation
History of Ministry of Health Funding for Disability Services
Health System Reforms
Chapter 5: Hope
Anthropology of Hope
Kerry and Powerchair Soccer
Miriam and the Medical Model
Chapter 6: Pain
Losing the Ability to Walk
Impact of DMD on Family Carers
Repeated Experience of Death
Chapter 7: Selective Reproductive Technologies
Natural Conception with Prenatal Screening and Termination
Natural Conception without Testing
Pre-implantation Genetic Diagnosis
Chapter 8: Acquisition of a Cough Assist Machine
Harry and his Cough Assist Machine
The Cough Assist Machine Assemblage
Analysis of the Cough Assist Machine Bureaucracy
Chapter 9: Powerchair and Support Worker Bureaucracies
Harry and his Wheelchair
The Wheelchair Assemblage
Problems with Eligibility Criteria
The Disparity between Capped Budgets and Disability Rights
Hidden Power of Eligibility Criteria
Pilot Schemes to Improve the Existing System
Others with DMD Who Lived Independently
Chapter 10: Care in Hospital
Usual Carers Provide the Best Support
Hospitals Struggle to Support People with DMD
Some Young Men are Particularly at Risk
Limited Health System Knowledge a Cause of Concern
Statutory Requirements for Person, Whanau or Patient-Centred Care
Chapter 11: Thesis Conclusions
Next Steps: Implications of the research
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