Reversed gender ratio of autism spectrum disorder in Smith-Magenis syndrome.

The sample was small: 28 participants total, with 27 analysed for the Social Communication Questionnaire, 28 for the Social Responsiveness Scale, 24 for the Vineland Adaptive Behavior Scale II, and 27 for the Developmental Behaviour Checklist. The study used parent-reported questionnaires about autism symptoms, not direct observation or diagnostic instruments such as the ADI-R or ADOS, so it does not say how many participants met criteria for autism spectrum disorder. Intellectual disability levels came from medical charts, with different testers, instruments, and ages of testing, so they were not reliable enough to drive the main conclusions. Adaptive behaviour was used as a proxy for developmental level, which is not the same as a formal IQ test. Families were recruited through rare-disorder and family-support organisations, and the study included about 47% of known Norwegian and about 55% of known Swedish Smith-Magenis syndrome cases, so the sample may not represent all people with the condition. The Social Responsiveness Scale was also influenced by behavioural problems, so autism symptom scores may partly reflect emotional and behavioural difficulties rather than autism symptoms alone. The study measured autism symptom scores, not the biological pathway that caused the gender difference. Because this was an assessment study, not an intervention study, it cannot show that any therapy or treatment changes autism symptoms.

Do not conclude that Smith-Magenis syndrome causes a female bias in autism or that females with the condition have more autism symptoms in all settings. The finding came from 28 participants recruited through family organisations, and the study used parent questionnaires rather than diagnostic observation, so it cannot establish a general rule.