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The prevalence of diseases causing childhood progressive intellectual and neurological deterioration in the UK is low (approximately 0.1/1000 live births). There were more than 220 different disorders, mainly genetically determined. The majority of disorders presented early in childhood: 81% before the age of 5 years. There were similarities in the disease spectrum in White and Pakistani children.
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Verity et al. (2020) studied this question.
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