Chromosomal Abnormalities

Chromosomal abnormalities are a very common cause of spontaneous miscarriage. Most commonly a child with a chromosomal abnormality will not survive to birth. However, there are many cases where the child will survive, although...

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Klinefelter’s Syndrome (47,XXY)

This is the presence of an extra X chromosome in males to give (47,XXY).  Epidemiology 1 in 1000 male live births Clinical features Usually diagnosed in childhood when there is: Clumsyness Learning difficulties (usually mild) Typically intellectual...

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Patterns of Disease Inheritance

Introduction Mendelian inheritance is a term sometimes used to describe patterns of inheritance, based on the original ideas of dominant and recessive genes, first proposed by the Gregorian Monk Mendel. Determining patterns of inheritance...

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Turner’s Syndrome (45, X)

Introduction In this condition there is only one X chromosome in the female. Epidemiology 95% of cases result in spontaneous miscarriage Present in 1 in 5000 Clinical features Vary widely from case to case....

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XXX Females

Approximately 0.1% of females have an extra X chromosome. It is likely that there will be no clinical features, however, some studies suggest that: intelligence is typically reduced by 10-20 IQ points. Special educational...

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XYY Males

Very similar to XXX in females. The incidence is again about 1 in 1000. They may have slightly reduced intellectual ability (10-20 IQ points), and a tendency for aggressive and criminal behaviour. Most cases...

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