Following the family get-together weekend many people wanted to know more about the inheritance of CGD and how it will affect their children.
Q. My son has X-linked CGD. What are the chances of him having affected children?
A. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons (no male-to-male transmission).
If your son has children with a partner who is not a carrier of CGD then:
- Boys will not be affected by the condition and they will not pass on the CGD gene to their children.
- All the girls will be carriers of CGD and will pass the CGD gene on to their off-spring.
Q. My daughter is a carrier of CGD. What are the chances of her having children with CGD?
A. If your daughter has children with a partner who is not affected genetically by CGD then:
For each pregnancy there is a 1 in 4 chance that they will have
- A boy who is affected by CGD and will have X-linked CGD.
- A boy who is unaffected by the condition and who will not pass on the condition to his children.
- A girl unaffected by CGD but will be a carrier of the CGD gene. She will pass this on to her offspring.
- A girl who will be unaffected by CGD and is not a carrier of the CGD gene.
Carriers of CGD having children
Q. I have another form of CGD called autosomal recessive CGD. Can you tell me how I inherited this?
A. This is inherited in a different way than X-linked CGD and is not linked to the sex of the person. You inherited two copies of the affected gene from both your parents who were both carriers of the condition. In autosomal recessive CGD the affected gene is present on chromosomes other than sex chromosomes. About 40% of all cases of CGD are inherited in this way. It is worth noting that autosomal recessive disorders are typically not seen in every generation of an affected family.
If each parent carries the defect in this way then for each pregnancy there is a
- 1 in 4 chance of having a child affected by CGD. This could affect a son or a daughter.
- 1 in 4 chance of having an unaffected child, a boy or girl, who is not a carrier.
- 1 in 2 chance that any child, boy or girl, will be a carrier of CGD.
Q. As I have autosomal CGD what are the chances of my children having CGD?
A. For you to also have affected children you would have to have children by a person who was also a carrier of CGD. This is highly unlikely unless the person is a close family member.
If this were to happen then your chances of having an affected child and offspring that carry the defective gene is the same as that above.
IMPORTANT NOTE :
The information contained on this website is intended only as a guideline, not as a substitute for medical advice. Always consult your doctor if you or your child has any CGD symptoms or concerns.
© 2001-2007 The Chronic Granulomatous Disorder (CGD) Research Trust
Registered Charity No. 1003425 email:cgd@cgdrt.co.uk
The CGD Research Trust is a member of the Association of Medical Research Charities (AMRC), the Genetic Interest Group (GiG) and an associate member of the International Patient Organisation of Primary Immunodeficiencies (IPOPI)
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