About Genetics and Screening
Disclaimer
Please note the information on this page does not replace individual medical advice or provides a diagnosis. If any parent or guardian visiting this site thinks their child has a form of Microcephalic Primordial Dwarfism, they should consult a local Clinical Geneticist or ask their local paediatrician/doctor to make a referral to one of our doctors on our Medical Advisory Board.
The Basics
The first 22 pairs are the same in men and women but the 23rd pair is different. Women have two ‘X’ chromosomes and men have one ‘X’ chromosome and one ‘Y’ chromosome. Along the chromosome are the individual instructions, or genes, that tell our bodies how to function.
Genes contains our genetic code or DNA (deoxyribonucleic acid). DNA is made up of four chemicals called bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
An important thing to remember is that we have no control over the changes in genes, there is nothing that was done to cause it and nothing that could have been done to prevent it.
We have over 20,000 genes in our body, each one performing a specific function. When we have children, we pass on only one copy of each of our genes. Typically, both copies from each parent are working. However, we all have genes that aren’t working as they should, that’s why there’s a backup one. If both copies of the gene aren’t working, then this causes the genetic condition to be expressed.
There are several ways in which genetic conditions can be passed down to children such as autosomal recessive, autosomal dominant and X-linked.
All the different types of Microcephalic Primordial Dwarfism (MPD) are thought to be caused by changes in genes. With increasing understanding and research in genetics we are able to find out more about which genes cause all the different types of MPD and how people are affected. Even individuals who have the same gene change can be affected differently than another, much like a spectrum. Many of the gene changes that express a form of MPD can also cause specific medical conditions. For example, it’s thought the gene change that causes MOPD II also causes changes to the tissues that make up blood vessels, and so can cause them to be weaker than average.
The specific order of these letters (bases) is what makes the instructions (genes) work properly. If one of these letters is changed, deleted or duplicated this change causes the gene to not work as usual.
Autosomal Recessive Inheritance
In many cases individuals with MPD inherit a specific gene with changes from each parent. This is called Autosomal Recessive Inheritance. Autosomal means the gene is found on one of the first 22 chromosomes (calls the autosomes) and not the X or Y chromosome (the sex chromosome).
With any Autosomal Recessive Inherited gene, the father is a carrier of the changed gene and the mother is also a carrier of the same changed gene. The parents themselves don’t express the condition because they only carry 1 copy of the gene that’s not working.
If both unaffected parents carry the same changed gene each child they have has:
- A 1 in 4 (25%) chance that a child will carry the changed gene from both parents and be affected with the condition.
- A 2 in 4 (50%) chance of inheriting one changed gene from either the mother or father (be a carrier) but wont be affected by the condition themselves.
- A 1 in 4 (25%) chance of not carrying any of the changed gene. These children will not be affected with the condition and not at risk of passing on the changed gene to their children.
For each child, regardless of their sex, the risk is the same.
Parents who are closely related to each other, such as close cousin marriage, share a large part of their genetic make-up and there is a higher chance they will have the same changed gene and be a carrier couple, and have a higher incidence of having children with a autosomal recessive condition.
X-Linked Inheritance
A few types of MPD have been found to be passed down by X-Linked Inheritance. X-Linked conditions occur when a changed gene is located on the X chromosome. If a woman has a changed gene on one of her two X chromosomes, then she will be a carrier and unaffected. She is unaffected as she has a second copy of the X chromosome with an unchanged gene working properly on it. If a man has an altered gene on his X chromosome, then he will be affected as he only has one X chromosome.
If a woman carrier has a boy:
- There is a 1in 2 (50%) risk that the boy will be affected by MPD.
If a woman carrier has a girl:
- There is a 1 in 2 (50%) risk that the girl will inherit the changed gene.
When men who are affected by X-Linked conditions have children:
- All of their daughters inherit the changed gene on their X chromosome. These daughters will be unaffected carriers.
- Men do not pass on their X chromosome to their sons. Therefore, all the sons of men with X-Linked conditions are unaffected.
What Is Genetic Counselling?
Genetic counselling is when health professionals help people understand and adapt to the medical, psychological and family implications of genetic conditions. It is not a therapeutic counselling service, but can give information about the risks of inheriting or passing on a condition, any genetic tests available and information about screening or other options that might be available in your area. Genetic counselling can be sought to help make sure you have all the information you need to make a informed decision that is right for your personal beliefs and family situation.
How Can I Be Referred For Genetic Counselling?
You can be referred through your:
- General Practitioner.
- Specialist Doctor.
- Other Professionals.
UK Regional Genetics Centre
The Midlands
Clinical Genetics Unit
Birmingham Womens Hospital
Metchley Park Road
Edgbaston
Birmingham
B15 2TG
Tel: 0121 335 8024
Email: genetics.info@nhs.net
Web Site: W Midlands Clinical Genetics Service
Catchment Areas: Staffordshire, Shropshire, Warwickshire, Birmingham, Hereford & Worcester and West Midlands
Department of Clinical Genetics
Leicester Royal Infirmary
Leicester
LE1 5WW
Tel: 0116 258 5736
Web Site: Leicestershire Clinical Genetics Service
Catchment Areas: Leicester, Nottingham and Northampton
Northern
Northern Genetics Service
The Newcastle upon Tyne Hospitals NHS Foundation Trust
Institute of Genetic Medicine International Centre for Life Central
Parkway
Newcastle upon Tyne
NE1 3BZ
Tel: 0191 241 8600
Web Site: Northern Region Genetics Service
Catchment Areas: Cleveland, Durham, Tyne & Wear, Northumberland and Cumbria.
The Yorkshire Regional Genetics Service
3rd Floor
Chapel Allerton Hospital
Chapeltown Road
Leeds
LS7 4SA
Tel: 0113 392 4432
Web Site: Yorkshire Regional Genetics Service
Catchment Areas: N Yorkshire, Bradford, W Yorshire, Leeds, Wakefield, E Riding, Grimsby and Scunthorpe.
Northern Ireland
Department of Medical Genetics
A Floor
Belfast City Hospital
Lisburn Road
Belfast
BT9 7AB
Tel: 028 9504 8022
Web Site: N Ireland Regional Genetic Service
Catchment Areas: Northern Ireland
North Thames
Clinical Genetics Department
Great Ormond Street Hospital for Children NHS Trust
Great Ormond Street
LONDON
WC1N 3JH
Tel: 020 7762 6831, 020 7762 6856, 020 7762 6786 and 020 7762 6845.
Web Site: N E Thames Regional Genetics Services
Catchment Areas: North and East London and Essex.
Kennedy Galton Centre
Level 8V
Northwick Park & St Marks NHS Trust
Watford Road
Harrow
Middlesex
HA1 3UJ
Tel: 020 8869 2795
Web Site: N W Thames Regional Genetics Service
Catchment Areas: Hertfordshire, Bedfordshire, Barnet, Hillingdon, Brent & Harrow, Ealing, Hammersmith, Hounslow, Kensington, Chelsea, Westminster and Edgware.
North West
Manchester Regional Genetics Service
Genetic Medicine
6th Floor
St Mary’s Hospital
CMFT
Oxford Rd
Manchester
M13 9WL
Tel: 0161 276 6506
Web Site: Manchester Regional Genetics Centre
Catchment Areas: Greater Manchester, Lancashire, Cumbria and Macclesfield.
Department of Clinical Genetics
Liverpool Women’s NHS Foundation Trust Service Base
Royal Children’s Hospita
Alder Hey
Eaton Road
Liverpool
L12 2AP
Tel: 0151 802 5001 or 0151 802 5002
Web Site:Cheshire and Merseyside Clinical Genetics Service
Catchment Areas: Liverpool, Wirral, Southport, St Helens & Knowsley, Warrington, Runcorn, Chester, Crewe and Isle of Man.
Anglia
Department of Clinical Genetics
PO Box 134
Addenbrooke’s Hospital NHS Trust
Cambridge
CB2 0QQ
Tel: 01223 216446
Web Site: East Anglia Regional Genetics Service
Catchment Areas: Cambridgeshire, Norfolk, Suffolk, parts of N Essex, Hertfordshire, Lincolnshire and Bedfordshire.
Oxford
Oxford Centre for Genomic Medicine
ACE building
Nuffield Orthopaedic Centre
Oxford University Hospitals NHS Foundation Trust
Windmill Road
Headington
Oxford
OX3 7HE
Tel: 01865 225931
Web Site:Oxford Regional Genetics Service
Catchment Areas: Oxfordshire, Northamptonshire, Buckinghamshire, Berkshire and Swindon.
Scotland
Human Genetics Unit
Level 6
Ninewells Hospital and Medical School
Dundee
DD1 9SY
Tel: 01382 632035
Web Site: E Scotland Human Genetic Laboratories
Catchment Areas: Dundee, Perth, N Fife, Angus and Perthshire
Department of Medical Genetics
Ashgrove House
Foresterhill
Aberdeen
AB25 2ZA
Tel: 01224 552120
Web Site: N Scotland Clinical Genetics Service
Catchment Areas: Grampian, Highland, Orkney & Shetland and Western Isles.
Department of Clinical Genetics
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU
Tel: 0131 537 1116
Web Site: S E Scotland Regional Genetics Centre
Catchment Areas: Lothian, Fife and Borders.
West of Scotland Clinical Genetic Service
Level 2A Laboratory Medicine
Southern General Hospital
1345 Govan Road
Glasgow
G51 4TF
Tel: 0141 354 9200 and 0141 354 9201
Web Site: West Scotland Regional Genetics Service
Catchment Areas: Greater Glasgow, Argyll & Clyde, Ayrshire & Arran, Forth Valley, Lanarkshire, and Dumfries & Galloway.
South Thames
The Genetics Department
7th Floor
New Guy’s House
Guy’s Hospital
London
SE1 9RT
Tel: 020 7188 1364
Web Site: S E Thames Regional Genetics Service
Catchment Areas: Kent, E Sussex, Bromley, Greenwich, Bexley, Lambeth, Southwark and Lewisham.
Department of Medical Genetics
St George’s University of London
Cranmer Terrace
London
SW17 0RE
Tel: 020 8725 2038
Web Site: S W Thames Regional Genetics Service
Catchment Areas: Ashford New River,South West London, Surrey and West Sussex
South West
Bristol Genetics Laboratory Pathology Sciences
Southmead Hospital
Westbury-on-Trym
Bristol
BS10 5NB
Tel: 0117 414 6168
Web Site: Bristol Clinical Genetics Service
Catchment Areas: Avon, Somerset, Gloucester and Cheltenham.
Clinical Genetics Department
Royal Devon & Exeter Hospital (Heavitree)
Gladstone Road
Exeter
EX1 2ED
Tel: 01392405726
Web Site: Peninsula Clinical Genetics Service
Catchment areas: Devon and Cornwall.
Princess Anne Hospital
Coxford Road
Southampton
SO16 5YA
Tel: 023 8120 6170
Web Site: Wessex Clinical Genetics Service
Catchment Areas: Hampshire, Dorset, Isle of Wight and Salisbury.
Trent
Nottingham Genetics Service
The Gables
Nottingham City Hospital NHS Trust
Hucknall Road
Nottingham
NG5 1PB
Tel: 0115 962 7728
Web Site: Nottingham Department of Clinical Genetics
Catchment areas: Nottingham, North Nottinghamshire, Lincolnshire, and North Derbyshire.
Department of Clinical Genetics
OPD2
Northern General Hospital
Herries Road
Sheffield
S5 7AU
Tel: 0114 271 7034
Web Site: Sheffield Clinical Genetics Service
Catchment Areas: Doncaster, Worksop, Barnsley, Chesterfield, Rotherham, Sheffield and Buxton.
Wales
Institute of Medical Genetics
University Hospital of Wales
Heath Park
Cardiff
CF14 4XW
Tel: 029 2074 2577
Web Site: All-Wales Medical Genetics Service
Catchment Areas: All of Wales.
International Genetics Centres (By Country)
Prenatal Testing
If you have a child with MPD or you have had a pregnancy diagnosis with a skeletal dysplasia you may have been tested for different MPD genes. If you know which gene change you carry your next pregnancy can be tested. There is no right or wrong answer when it comes to genetic testing. It is a personal choice for you and your family
What Is Prenatal Testing?
Prenatal testing is the genetic testing a foetus during pregnancy. Testing can be offered by either a chorionic villus sample (CVS) or by an amniocentesis.
What Are The Risks Of Having A Prenatal Test?
We know that sometimes the test can cause a miscarriage.
- Approximately 1 in every 50 (2%) women who have a CVS will miscarry as a result of the procedure.
- Approximately 1 in every 200 (0.5%) women who have an amniocentesis will miscarry as a result of the procedure.
As the test is carried out under ultrasound guidance other than this there is no evidence that prenatal testing is harmful to the baby.
When Is Prenatal Testing Carried Out?
CVS is carried out around 9 – 12 weeks of pregnancy. Amniocentesis is carried out around 16 weeks of pregnancy.
How Is The Test Carried Out?
The test involves taking a small amount of placental tissue (for a CVS) or amniotic fluid that surrounds the baby in the womb (for an amniocentesis). Under ultrasound guidance, a fine needle is passed through the abdomen into the womb and a sample of the tissue or fluid is removed. This contains cells from the baby that are tested in the laboratory.
When Will The Results Be Ready?
Your own clinician will let you know how long the results might take, depending on your hospital. Very occasionally (1-2% of cases) the results are not clear and the test may need to be repeated.
What If The Results Show The Baby Has The Gene Change?
Your specialist doctor or midwife will explain what the results mean and talk to you about your options.
Deciding whether or not to carry on with the pregnancy can be a very difficult and hard decision and only one which you and your family can make together. You may find you feel differently from one day to the other and you do not the to make the decision on your own. There is no right or wrong in your decision, only what’s best for you and your family.
For further information on continuing with your pregnancy or choosing a termination, please visit this page: https://www.nhs.uk/conditions/pregnancy-and-baby/what-if-antenatal-screening-finds-a-problem/
MPD Sub-Types
Familes Supported
Countries
Amazing people
Frequently Asked Questions:
I think our child has Microcephalic Primordial Dwarfism. Can you help us?
Yes we can! All you need to do is send an email to Sue Connerty at sue.connerty@walkingwithgiants.org and she will get back to you via email asking some information about your child. On receipt of your reply, she will the assess the information and consult with doctors on our Medical Advisory Board. If all information corresponds with the criteria needed for the WWGF to your child and your family, The WWGF will then send you some information how to regisiter for support and unite with other families affected by Microcephalic Primordial Dwarifism.
How can I help the Walking With Giants Foundation?
How do I make a donation?
There are several ways that you can make a donation, please visit our 'Making A Donation' page.
If you would like your donation to be recognised please let us know by:
Calling us 0151 526 0134 (from within the UK),
Calling us +44 151 526 0134 (from outside of the UK),
Email us on enquiries@walkingwithgiants.org,
or by writing to us at, Walking With Giants Foundation, PO Box 85, Maghull, Liverpool, L31 6WW.