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DIGEORGE SYNDROME is a rare congenital (i.e. present at birth)
disease whose symptoms vary greatly between individuals, but
commonly include a history of recurrent infection, heart defects
and characteristic facial features.
DiGeorge syndrome is caused by a large deletion from
chromosome 22, produced by an error in recombination at
meiosis (the process that creates germ cells and ensures
genetic variation in the offspring). This deletion means that several genes from this region are not present in DiGeorge syndrome patients. It appears that the variation in the symptoms of
the disease is related to the amount of genetic material lost in the chromosomal deletion.
Although researchers now know that the DGS gene is required
for the normal development of the thymus and related glands,
counteracting the loss of DGS is difficult. Some effects, for
example, the cardiac problems and some of the speech
impairments, can be treated either surgically or therapeutically,
but the loss of immune-system T-cells (produced by the
thymus) is more challenging, and requires further research on
recombination and immune function.