Transcript X Linked Inheritance Transmission patterns © 2009 NHS National Genetics Education and Development Centre Genetics and Genomics for Healthcare www.geneticseducation.nhs.uk.

X Linked Inheritance
Transmission patterns
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk
Pedigree of Martin Davies’s family.
Assuming this is X-linked muscular dystrophy, the women marked with dots are obligate carriers of the disease
gene – that is, they must be carriers because they have both parents and offspring who are affected or carriers.
Fig. 1.10 ©Scion Publishing Ltd
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk
Pedigree of an X-linked dominant condition.
Although heterozygous females are affected, such conditions are usually milder and more variable in females
than in males.
Fig. 1.16 ©Scion Publishing Ltd
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk
Tracking the inheritance of the gene causing Duchenne
muscular dystrophy through the family
X-chromosomes shown
Therefore, Anne is not a carrier for
Duchenne muscular dystrophy
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk
X chromosomes only are shown
This pedigree pattern can be explained by deducing the inheritance of the maternal X
chromosomes
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk
X chromosomes only are shown
or
An equal chance of being a carrier or not
© 2009 NHS National Genetics Education and Development Centre
Genetics and Genomics for Healthcare
www.geneticseducation.nhs.uk