About Genetics and Screening


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

Our bodies are made up of billions of different cells, for example skin cells and brain cells and muscle cells. They all have a different specific function in our bodies, but each cell carries a set of 46 chromosomes, or 23 pairs.

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).

genetics and screening Image 1

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.

WWGF Genetics and Screening Image 2 Autosomal Recessive Inheritance

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.

WWGF Genetics and Screening X Linked Inheritance

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
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

Tel: 0116 258 5736
Web Site: Leicestershire Clinical Genetics Service 

Catchment Areas: Leicester, Nottingham and Northampton


Northern Genetics Service
The Newcastle upon Tyne Hospitals NHS Foundation Trust
Institute of Genetic Medicine International Centre for Life Central
Newcastle upon Tyne

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

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

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

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

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
Oxford Rd
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
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.


Department of Clinical Genetics
PO Box 134
Addenbrooke’s Hospital NHS Trust

Tel: 01223 216446
Web Site: East Anglia Regional Genetics Service

Catchment Areas: Cambridgeshire, Norfolk, Suffolk, parts of N Essex, Hertfordshire, Lincolnshire and Bedfordshire.


Oxford Centre for Genomic Medicine
ACE building
Nuffield Orthopaedic Centre
Oxford University Hospitals NHS Foundation Trust
Windmill Road

Tel: 01865 225931
Web Site:Oxford Regional Genetics Service 

Catchment Areas: Oxfordshire, Northamptonshire, Buckinghamshire, Berkshire and Swindon.


Human Genetics Unit
Level 6
Ninewells Hospital and Medical School
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
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

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
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

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
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
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

Tel: 01392405726
Web Site: Peninsula Clinical Genetics Service

Catchment areas: Devon and Cornwall.

Princess Anne Hospital
Coxford Road
SO16 5YA

Tel: 023 8120 6170
Web Site: Wessex Clinical Genetics Service

Catchment Areas: Hampshire, Dorset, Isle of Wight and Salisbury.


Nottingham Genetics Service
The Gables
Nottingham City Hospital NHS Trust
Hucknall Road

Tel: 0115 962 7728
Web Site: Nottingham Department of Clinical Genetics

Catchment areas: Nottingham, North Nottinghamshire, Lincolnshire, and North Derbyshire.

Department of Clinical Genetics
Northern General Hospital
Herries Road
S5 7AU

Tel: 0114 271 7034
Web Site: Sheffield Clinical Genetics Service

Catchment Areas: Doncaster, Worksop, Barnsley, Chesterfield, Rotherham, Sheffield and Buxton.


Institute of Medical Genetics
University Hospital of Wales
Heath Park
CF14 4XW

Tel: 029 2074 2577
Web Site: All-Wales Medical Genetics Service

Catchment Areas: All of Wales.

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/

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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?
There are many ways to help the Walking With GIants Foundation. Please visit our 'Get Involved' page. If there is something that you would like do for the WWGF, we would love to her from you. Please send us an email on enquiries@walkingwithgiants.org with you ideas or specific area of support.
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),

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Email us on enquiries@walkingwithgiants.org,

or by writing to us at, Walking With Giants Foundation, PO Box 85, Maghull, Liverpool, L31 6WW.