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Which inheritance pattern do the sexes affected and the generations skipped point to?
More, if you want it
How does the condition pass through the patient's family?Tap a term: its definition, what you can do with it, and how often the exam asks it.
Definition: a pattern where one altered copy causes the condition, seen down the generations.
You can: Tell autosomal dominant inheritance from autosomal recessive inheritance by whether the condition passes down the generations.
Definition: a pattern where unaffected carrier parents have affected children, and generations can be skipped.
You can: Tell autosomal recessive inheritance from autosomal dominant inheritance by unaffected carrier parents and skipped generations.
Definition: an X chromosome pattern seen in Rett syndrome and vitamin D-resistant rickets.
You can: Tell X-linked dominant inheritance from X-linked recessive inheritance by the named condition, such as Rett syndrome.
Definition: an X chromosome pattern seen in Duchenne muscular dystrophy and haemophilia.
You can: Tell X-linked recessive inheritance from X-linked dominant inheritance by the named condition, such as Duchenne muscular dystrophy.
Definition: a pattern passed from the mother only, as in LHON.
You can: Tell mitochondrial inheritance from X-linked inheritance by passing from the mother only.
Each card is one term. The grey line is what the patient says, which is what the question stem gives.
Summary
Autosomal dominant inheritance is a pattern where the condition passes down the generations in both sexes.
inheritance is a pattern where the condition passes down the generations in both sexes. A is a family tree that marks each affected relative. Working out the pedigree's pattern means checking skipped generations, sex distribution and .
The first check asks whether the condition skips generations. The second check asks whether both sexes are affected equally. The third check asks whether an affected father passes the condition to a son, called male-to-male transmission.
Pedigree patterns do not always fit one neat label.
Mr Daniel Okafor attends a neurology clinic with jerky movements. Mr Okafor says, "My father had Huntington's, and so did my grandmother."
Autosomal dominant conditions include Huntington's disease, neurofibromatosis, Marfan's syndrome and achondroplasia. A condition seen in each generation, in men and women, fits autosomal dominant inheritance.
Neurofibromatosis and tuberous sclerosis are autosomal dominant causes of intellectual disability.
5 more sections on Autosomal dominant, autosomal recessive, X-linked and mitochondrial inheritance
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