5

Contact us If you live in the South East Thames Region: Clinical Genetics Department, 7th Floor, Borough Wing, Guy’s Hospital, Great Maze Pond, London SE1 9RT t: 020 7188 1364, f: 020 7188 1369 w: www.guysandstthomas.nhs.uk/genetics

Both boys and girls who inherit this X will

not be carriers or affected by DMD.

If a mother is a carrier of DMD If a woman has an alteration in the DMD gene on one of her X chromosomes, she is known as a carrier of DMD. Females have two X chromosomes, but can only pass on one to each of their children. A mother who is a carrier of DMD has a 1 in 2 (50%) chance of passing on either her normal X chromosome or the one that carries the altered copy of the dystrophin gene. Each of her sons has a 1 in 2 (50%) chance of developing DMD, and each of her daughters has a 1 in 2 (50%) chance of being a carrier of DMD.

Carrier mother X X

Heart screening for carriers Some women who are carriers of DMD develop heart problems. Cardiac screening is recommended every five years for carriers of DMD.

Tests during pregnancy It may be possible to have a test during pregnancy to discover if a baby has inherited the DMD gene. If you would like to find out more about these tests, please ask to speak to a genetic counsellor or doctor.

Useful sources of information Muscular Dystrophy Campaign Information and support line: 0800 652 6352 w: www.muscular-dystrophy.org The Duchenne Family Support Group Helpline: 0800 121 4518 w: www.dfsg.org.uk e: info@dfsg.org.uk

Your comments and concerns For advice, support or to raise a concern, contact our Patient Advice and Liaison Service (PALS). To make a complaint, contact the complaints department. t: 020 7188 8801 (PALS) e: pals@gstt.nhs.uk t: 020 7188 3514 (complaints) e: complaints2@gstt.nhs.uk

Duchenne muscular dystrophy (DMD) This leaflet gives information about DMD and how it is passed on to your children.

Leaflet number: 2111/VER2 Date published: June 2019

Review date: June 2020 © 2019 Guy’s and St Thomas’ NHS Foundation Trust

A list of sources is available on request

Boys who inherit this X will develop DMD. Girls who inherit this

X will be carriers of DMD.

2 3 4

What is DMD?

DMD is a condition that affects all the muscles of the body, causing them to become progressively weaker. It is caused by a change in a gene called dystrophin. The dystrophin gene normally makes a protein that is essential for keeping the muscles strong and healthy. If the dystrophin gene has a mutation (change), this protein does not get made. This means that your body cannot replace damaged muscle tissue or to grow new muscle cells. DMD is a very serious condition. Boys with DMD usually begin to have difficulty walking by the age of three and are unable to run and jump like other children. They often struggle to climb stairs and to rise from the floor. Some boys also have mild learning or behavioural difficulties. By their early teens, most boys with DMD will require a wheelchair. By their late teens or early twenties, the condition often affects the breathing muscles and is usually severe enough to shorten life expectancy. Although there is no cure for DMD at the moment, research is being done to find a cure and effective treatments for DMD. About 100 boys with DMD are born in the UK each year. There are about 1,500 boys known to have the disorder living in the UK at any one time. About 1 in every 3,500 male births is affected by DMD. How is DMD diagnosed? DMD is often diagnosed after parents notice their child is having problems with walking or

other physical activities. A blood test will reveal a very high level of the enzyme creatine kinase. A muscle biopsy may also be necessary to confirm the diagnosis. Once DMD is confirmed, genetic testing is often offered to identify the exact gene alteration. If a gene alteration is identified, other family members can be tested to see if they are carriers of DMD. In a small number of cases, no change in the dystrophin gene can be found with current testing methods. What are genes and chromosomes? Genes are the unique set of ‘instructions’ inside our bodies which makes each of us different. There are many thousands of different genes. Each one carries a different instruction. As well as determining how we look, our genes control the way each cell, or building block, of the body works. Genes are made of DNA. DNA is tightly coiled into structures called chromosomes. Each chromosome has about a thousand genes. Most of our body cells have 46 chromosomes, arranged in 23 pairs. 22 pairs are the same in men and women. The remaining pair are the sex chromosomes as they determine if you are male or female. Females have two X chromosomes, and males have one X and one Y chromosome. We inherit (receive) one of each chromosome pair from our mother, and the other from our father. Men always inherit their X chromosome from their mother and their Y chromosome from their father.

How is DMD inherited? Most boys with DMD inherit the changed gene from their mother. In about one-third of cases, the gene alteration is not inherited but happens for the first time when the boy is conceived. A lot more boys have DMD, than girls. Will a children inherit the DMD gene? If a father has DMD: Men who have DMD have an altered copy of the dystrophin gene on their X chromosome. Men with DMD are not usually able to have children because they do not live long enough to become fathers. If a man with DMD has children, all of his daughters would be carriers of DMD. This is because men always pass their only X chromosome on to their daughters. His sons would not be affected because they would inherit their father’s healthy Y chromosome.

Father with DMD X Y

All of this man’s children who inherit his X chromosome will be girls who are

carriers of DMD.

All of this man’s children who inherit his Y chromosome

will be healthy boys.

2 3 4

What is DMD?

DMD is a condition that affects all the muscles of the body, causing them to become progressively weaker. It is caused by a change in a gene called dystrophin. The dystrophin gene normally makes a protein that is essential for keeping the muscles strong and healthy. If the dystrophin gene has a mutation (change), this protein does not get made. This means that your body cannot replace damaged muscle tissue or to grow new muscle cells. DMD is a very serious condition. Boys with DMD usually begin to have difficulty walking by the age of three and are unable to run and jump like other children. They often struggle to climb stairs and to rise from the floor. Some boys also have mild learning or behavioural difficulties. By their early teens, most boys with DMD will require a wheelchair. By their late teens or early twenties, the condition often affects the breathing muscles and is usually severe enough to shorten life expectancy. Although there is no cure for DMD at the moment, research is being done to find a cure and effective treatments for DMD. About 100 boys with DMD are born in the UK each year. There are about 1,500 boys known to have the disorder living in the UK at any one time. About 1 in every 3,500 male births is affected by DMD. How is DMD diagnosed? DMD is often diagnosed after parents notice their child is having problems with walking or

other physical activities. A blood test will reveal a very high level of the enzyme creatine kinase. A muscle biopsy may also be necessary to confirm the diagnosis. Once DMD is confirmed, genetic testing is often offered to identify the exact gene alteration. If a gene alteration is identified, other family members can be tested to see if they are carriers of DMD. In a small number of cases, no change in the dystrophin gene can be found with current testing methods. What are genes and chromosomes? Genes are the unique set of ‘instructions’ inside our bodies which makes each of us different. There are many thousands of different genes. Each one carries a different instruction. As well as determining how we look, our genes control the way each cell, or building block, of the body works. Genes are made of DNA. DNA is tightly coiled into structures called chromosomes. Each chromosome has about a thousand genes. Most of our body cells have 46 chromosomes, arranged in 23 pairs. 22 pairs are the same in men and women. The remaining pair are the sex chromosomes as they determine if you are male or female. Females have two X chromosomes, and males have one X and one Y chromosome. We inherit (receive) one of each chromosome pair from our mother, and the other from our father. Men always inherit their X chromosome from their mother and their Y chromosome from their father.

How is DMD inherited? Most boys with DMD inherit the changed gene from their mother. In about one-third of cases, the gene alteration is not inherited but happens for the first time when the boy is conceived. A lot more boys have DMD, than girls. Will a children inherit the DMD gene? If a father has DMD: Men who have DMD have an altered copy of the dystrophin gene on their X chromosome. Men with DMD are not usually able to have children because they do not live long enough to become fathers. If a man with DMD has children, all of his daughters would be carriers of DMD. This is because men always pass their only X chromosome on to their daughters. His sons would not be affected because they would inherit their father’s healthy Y chromosome.

Father with DMD X Y

All of this man’s children who inherit his X chromosome will be girls who are

carriers of DMD.

All of this man’s children who inherit his Y chromosome

will be healthy boys.

2 3 4

What is DMD?

DMD is a condition that affects all the muscles of the body, causing them to become progressively weaker. It is caused by a change in a gene called dystrophin. The dystrophin gene normally makes a protein that is essential for keeping the muscles strong and healthy. If the dystrophin gene has a mutation (change), this protein does not get made. This means that your body cannot replace damaged muscle tissue or to grow new muscle cells. DMD is a very serious condition. Boys with DMD usually begin to have difficulty walking by the age of three and are unable to run and jump like other children. They often struggle to climb stairs and to rise from the floor. Some boys also have mild learning or behavioural difficulties. By their early teens, most boys with DMD will require a wheelchair. By their late teens or early twenties, the condition often affects the breathing muscles and is usually severe enough to shorten life expectancy. Although there is no cure for DMD at the moment, research is being done to find a cure and effective treatments for DMD. About 100 boys with DMD are born in the UK each year. There are about 1,500 boys known to have the disorder living in the UK at any one time. About 1 in every 3,500 male births is affected by DMD. How is DMD diagnosed? DMD is often diagnosed after parents notice their child is having problems with walking or

other physical activities. A blood test will reveal a very high level of the enzyme creatine kinase. A muscle biopsy may also be necessary to confirm the diagnosis. Once DMD is confirmed, genetic testing is often offered to identify the exact gene alteration. If a gene alteration is identified, other family members can be tested to see if they are carriers of DMD. In a small number of cases, no change in the dystrophin gene can be found with current testing methods. What are genes and chromosomes? Genes are the unique set of ‘instructions’ inside our bodies which makes each of us different. There are many thousands of different genes. Each one carries a different instruction. As well as determining how we look, our genes control the way each cell, or building block, of the body works. Genes are made of DNA. DNA is tightly coiled into structures called chromosomes. Each chromosome has about a thousand genes. Most of our body cells have 46 chromosomes, arranged in 23 pairs. 22 pairs are the same in men and women. The remaining pair are the sex chromosomes as they determine if you are male or female. Females have two X chromosomes, and males have one X and one Y chromosome. We inherit (receive) one of each chromosome pair from our mother, and the other from our father. Men always inherit their X chromosome from their mother and their Y chromosome from their father.

How is DMD inherited? Most boys with DMD inherit the changed gene from their mother. In about one-third of cases, the gene alteration is not inherited but happens for the first time when the boy is conceived. A lot more boys have DMD, than girls. Will a children inherit the DMD gene? If a father has DMD: Men who have DMD have an altered copy of the dystrophin gene on their X chromosome. Men with DMD are not usually able to have children because they do not live long enough to become fathers. If a man with DMD has children, all of his daughters would be carriers of DMD. This is because men always pass their only X chromosome on to their daughters. His sons would not be affected because they would inherit their father’s healthy Y chromosome.

Father with DMD X Y

All of this man’s children who inherit his X chromosome will be girls who are

carriers of DMD.

All of this man’s children who inherit his Y chromosome

will be healthy boys.

5

Contact us If you live in the South East Thames Region: Clinical Genetics Department, 7th Floor, Borough Wing, Guy’s Hospital, Great Maze Pond, London SE1 9RT t: 020 7188 1364, f: 020 7188 1369 w: www.guysandstthomas.nhs.uk/genetics

Both boys and girls who inherit this X will

not be carriers or affected by DMD.

If a mother is a carrier of DMD If a woman has an alteration in the DMD gene on one of her X chromosomes, she is known as a carrier of DMD. Females have two X chromosomes, but can only pass on one to each of their children. A mother who is a carrier of DMD has a 1 in 2 (50%) chance of passing on either her normal X chromosome or the one that carries the altered copy of the dystrophin gene. Each of her sons has a 1 in 2 (50%) chance of developing DMD, and each of her daughters has a 1 in 2 (50%) chance of being a carrier of DMD.

Carrier mother X X

Heart screening for carriers Some women who are carriers of DMD develop heart problems. Cardiac screening is recommended every five years for carriers of DMD.

Tests during pregnancy It may be possible to have a test during pregnancy to discover if a baby has inherited the DMD gene. If you would like to find out more about these tests, please ask to speak to a genetic counsellor or doctor.

Useful sources of information Muscular Dystrophy Campaign Information and support line: 0800 652 6352 w: www.muscular-dystrophy.org The Duchenne Family Support Group Helpline: 0800 121 4518 w: www.dfsg.org.uk e: info@dfsg.org.uk

Your comments and concerns For advice, support or to raise a concern, contact our Patient Advice and Liaison Service (PALS). To make a complaint, contact the complaints department. t: 020 7188 8801 (PALS) e: pals@gstt.nhs.uk t: 020 7188 3514 (complaints) e: complaints2@gstt.nhs.uk

Duchenne muscular dystrophy (DMD) This leaflet gives information about DMD and how it is passed on to your children.

Leaflet number: 2111/VER2 Date published: June 2019

Review date: June 2020 © 2019 Guy’s and St Thomas’ NHS Foundation Trust

A list of sources is available on request

Boys who inherit this X will develop DMD. Girls who inherit this

X will be carriers of DMD.

5

Contact us If you live in the South East Thames Region: Clinical Genetics Department, 7th Floor, Borough Wing, Guy’s Hospital, Great Maze Pond, London SE1 9RT t: 020 7188 1364, f: 020 7188 1369 w: www.guysandstthomas.nhs.uk/genetics

Both boys and girls who inherit this X will

not be carriers or affected by DMD.

If a mother is a carrier of DMD If a woman has an alteration in the DMD gene on one of her X chromosomes, she is known as a carrier of DMD. Females have two X chromosomes, but can only pass on one to each of their children. A mother who is a carrier of DMD has a 1 in 2 (50%) chance of passing on either her normal X chromosome or the one that carries the altered copy of the dystrophin gene. Each of her sons has a 1 in 2 (50%) chance of developing DMD, and each of her daughters has a 1 in 2 (50%) chance of being a carrier of DMD.

Carrier mother X X

Heart screening for carriers Some women who are carriers of DMD develop heart problems. Cardiac screening is recommended every five years for carriers of DMD.

Tests during pregnancy It may be possible to have a test during pregnancy to discover if a baby has inherited the DMD gene. If you would like to find out more about these tests, please ask to speak to a genetic counsellor or doctor.

Useful sources of information Muscular Dystrophy Campaign Information and support line: 0800 652 6352 w: www.muscular-dystrophy.org The Duchenne Family Support Group Helpline: 0800 121 4518 w: www.dfsg.org.uk e: info@dfsg.org.uk

Your comments and concerns For advice, support or to raise a concern, contact our Patient Advice and Liaison Service (PALS). To make a complaint, contact the complaints department. t: 020 7188 8801 (PALS) e: pals@gstt.nhs.uk t: 020 7188 3514 (complaints) e: complaints2@gstt.nhs.uk

Duchenne muscular dystrophy (DMD) This leaflet gives information about DMD and how it is passed on to your children.

Leaflet number: 2111/VER2 Date published: June 2019

Review date: June 2020 © 2019 Guy’s and St Thomas’ NHS Foundation Trust

A list of sources is available on request

Boys who inherit this X will develop DMD. Girls who inherit this

X will be carriers of DMD.