Chapter 9 Multiple choice questions

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What is known about the epidemiology of intellectual disability? Select all correct answers.

About 2% of the population has mild intellectual disability correct incorrect

Girls are more commonly affected than boys correct incorrect

Severe forms are more likely to be due to a single cause correct incorrect

Mild forms are often attributed to birth injury correct incorrect

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What can cause Down syndrome? Select all correct answers.

The presence of three entire copies of chromosome 21 correct incorrect

Translocations involving chromosome 21 correct incorrect

Partial deletions of chromosome 21 correct incorrect

Partial duplications of chromosome 21 correct incorrect

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How does trisomy 21 cause Down syndrome? Select correct answer.

By the overexpression of a small number of genes in a critical region of chromosome 21 correct incorrect

By the overexpression of about 200 genes on chromosome 21 correct incorrect

By the change in expression of about 200 genes spread across the genome correct incorrect

By epigenetic changes arising from the presence of an additional chromosome correct incorrect

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What has the study of copy number variants revealed about the genetic basis of intellectual disability? Select all correct answers.

CNVs (deletions and insertions) are more common in children with intellectual disability than in controls correct incorrect

Recurrent rearrangements are a cause of intellectual disability correct incorrect

CNVs are the single most important cause of intellectual disability correct incorrect

Phenotypic variability is explained by the presence of additional CNVs correct incorrect

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What causes Fragile X syndrome? Select correct answer.

An unknown chromosomal fragility syndrome correct incorrect

A small deletion on the X chromosome correct incorrect

Expansion of a trinucleotide repeat correct incorrect

A duplication of part of the X chromosome correct incorrect

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What is known about the mutations that cause non-syndromal intellectual disability? Select all correct answers.

They lie exclusively in non-coding regions of the genome correct incorrect

In families where multiple members have intellectual disability, the mutation often has an X-linked pattern of inheritance correct incorrect

All the mutations are in the same biological pathway correct incorrect

De novo mutations are an important contributor correct incorrect

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What is MeCP2 and what have mutations in this gene told us? Select all correct answers.

MeCP2 is an enzyme involved in the metabolism of neurotransmitters correct incorrect

MeCP2 is methyl-CpG-binding protein 2, which binds to methylated DNA, and represses transcription correct incorrect

Mutations in MeCP2 cause Rett syndrome correct incorrect

Reversing the effect of the mutation is possible, as shown by genetically repairing the mutation in a mouse correct incorrect

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What do we know about the inheritance of mutations that cause intellectual disability? Select all correct answers.

20% of mutations that cause intellectual disability are dominant correct incorrect

5% of mutations that cause intellectual disability are recessive correct incorrect

20% of mutations that cause intellectual disability are X-linked correct incorrect

The commonest genetic cause of intellectual disability is polygenic inheritance correct incorrect

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What have genetic studies told us about the biology of intellectual disability? Select all correct answers.

Nothing of consequence correct incorrect

They have identified a key set of pathways involved in cognitive function correct incorrect

The genes involved have varied functions, reflecting the heterogeneity of the condition correct incorrect

They are being used to guide the design of new therapies correct incorrect

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What has been discovered about the genetic basis of intellectual disability? Select all correct answers.

Almost one fifth of the genes that cause intellectual disability also cause ASD correct incorrect

A small number of genes that cause intellectual disability have also been implicated in schizophrenia correct incorrect

Non specificity of genetic action is common correct incorrect

Many of the genes are involved in epigenetic processes correct incorrect