A 6-year-old boy has autistic features, hyperactivity, and inattention. He is noted to have frequent self-injurious head banging and nail pulling. There is a history of both nocturnal and diurnal enuresis. He has an IQ in the range of moderate learning disability. He has normal uric acid levels in his serum.
The most likely cause is:
C. Smith–Magenis syndrome has a prevalence of 1: 500 000. It is caused by a microdeletion on the short arm of chromosome 17p11·2. The degree of intellectual impairment is usually variable. The phenotype includes bradydactyly, a broad, fl at face, hoarse voice, and a characteristic fleshy upper lip, although these features may be very subtle. Prominent autistic features, hyperactivity (in 75%), inattention, and self-injury (in 70%) such as head banging, nail pulling, and hand biting, are seen. Nocturnal and diurnal enuresis may also be present. Sleep is characterized by reduced or absent REM phase. Trisomy 21 refers to Down’s syndrome. 7q11 deletion in the elastin gene can result in Williams syndrome, which is characterized by hyperactivity, ‘cocktail party speech’, and supravalvular aortic stenosis. Hypoxanthine guanine phosphoribosyltransferase deficiency can result in Lesch Nyhan syndrome with severe self-mutilation, aggression, and hyperuricaemia. Trisomy 13 syndrome is also known as Patau’s syndrome and can be of three types: full trisomy, mosaic pattern type, and translocation type. All survivors have profound mental retardation.
The most powerful predictor of overall functional outcome in children with autism is given by:
D. Autism is a disorder with lifelong disability. About 70% of autistic individuals have an IQ in the learning disability range. In autism, IQ has been shown to be the most powerful predictor of outcome. A distinctive cognitive profile characterized by strong visuospatial skills and poor abstract ability has been noted. A small proportion of autistic children may have islets of special abilities and are dubbed as ‘autistic savants’. The presence of communicative speech by the age of 5 years is another important predictor of positive outcome.
Which of the following groups of school children develops a higher prevalence of psychopathology as adults than the others listed?
D. In a sample of more than 2500 boys born in 1981, details of bullying and victimization were gathered when the boys were 8 years old. Between the ages of 18 and 23, information about psychiatric disorders was collected from a registry. The boys could be classified into those who bully others, those who are frequently victimized, and those who bully others and are victimized frequently. Frequent bullying-only status predicted antisocial personality and substance abuse; frequent victimization-only status predicted anxiety disorder, whereas frequent bully– victim status predicted antisocial personality and anxiety disorder. Frequent bully–victims were at particular risk of adverse long-term outcomes compared with either pure bullies or pure victims.
The most common known inherited cause of learning disability is:
B. Fragile X syndrome is the most common known inherited cause of learning disability. It affects 1:3600 boys and 1:6000 girls. Thirty per cent of individuals affected by fragile X have autistic features. Nearly 20% have epilepsy too. 1 in 300 women and 1 in 800 men are carriers of fragile X mutation. Although Down’s syndrome is a more common cause of learning disability, it is mostly sporadic and not inherited in the strict sense.
The point prevalence of schizophrenia in people with learning disability is:
C. The point prevalence of schizophrenia is estimated to be between 3% and 4% in the learning-disabled population compared with 1% in the general population. Schizophrenia cannot be reliably diagnosed below an IQ of approximately 45. Often in clinical practice, if there is evidence of delusions or hallucinations in those with profound learning disability, a diagnosis of psychosis not otherwise specified is used. Despite this the rate of schizophrenia is significantly higher among the population with learning disability. This increase is seen despite the overall rate of psychiatric illness among adults with mild to moderate learning disability being similar to that in the general adult population without learning disability. The reason for this increased comorbidity is unclear, and common underlying brain damage that could cause both learning disability and schizophrenia cannot be ruled out.
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