Answer to Question 1
Similar to racial differences in the diagnosis of intellectual disability, gender differences in ID may be an artifact of identification and referral patterns rather than true differences in prevalence (Einfeld et al., 2010). If a true male excess of intellectual disability does exist, researchers suspect this may be due to the occurrence of X-linked genetic disorders such as fragile-X syndrome (discussed later in the chapter), which affect males more often than females (Handen, 2007).
Answer to Question 2
As a group, children with mild intellectual disability typically develop social and communication skills during the preschool years (aged 05 years), perhaps with modest delays in expressive language. They usually have minimal or no sensorimotor impairment and engage with peers readily. During their adult years, they usually achieve social and vocational skills adequate for minimum self-support, but may need supervision, guidance, and assistance, especially when under unusual social or economic stress. Persons with moderate intellectual disability constitute about 10 of individuals with ID. Children and adolescents at this level of impairment are more intellectually and adaptively impaired than someone with mild intellectual disability, and usually they are identified during the preschool years, when they show delays in reaching early developmental milestones. Because their social judgment and decision-making abilities are limited, children and youth with moderate ID often require supportive services to function on a daily basis. Those with severe intellectual disability constitute approximately 4 of persons with ID. Most of these individuals suffer one or more organic causes of impairment, such as genetic defects, and are identified at a very young age because they have substantial delays in development and visible physical features or anomalies. Most persons functioning at the severe level of intellectual disability require some special assistance throughout their lives. Persons with profound intellectual disability constitute approximately 2 of those with ID. Such individuals typically are identified in infancy because of marked delays in development and biological anomalies such as asymmetrical facial features. Persons with profound intellectual disability require lifelong care and assistance.
Risk of death from motorcycle accidents (dashed lines) and passenger accidents (solid lines) per 100
The “Infertility Belt” In certain countries in Central Africa, infertility rates are as high as 30%
Although the highest rates of disordered eating patterns occur among females, males are not immune
A pedigree for an X-linked dominant trait. Affected males produce all affected daughters and no affe
Meiosis in Males and Females
Mosaic X Chromosome Expression in Human Females