Autism is a neurodevelopmental disorder which manifests in early childhood. The prevalence of the diseases belonging to the spectrum of autism has been estimated at 1/167; it is four times more frequent in boys than in girls. Autism is characterized by qualitative deficiencies in social interactions and verbal and nonverbal communication skills, as well as repetitive and stereotyped patterns of behavior. Autism is a wide-spectrum disorder which means no two people will have exactly the same symptoms; the severity also varies in autistic patients. Children with autism may be overly sensitive in sight, hearing, touch, smell, or taste; they also have unusual distress when routines are changed, they perform repeated body movements, they may not respond to eye contact or smiles, or may avoid eye contact and show unusual attachments to objects.
The etiology of autism is unknown. Given the complexity of the disease, and the fact that symptoms and severity vary, there are many hypotheses including genetic abnormalities, obstetric complications, exposure to toxic agents, and prenatal, perinatal, and postnatal infections.
Autism is linked to identified genetic diseases in 10-25% of the cases. Also, many genes and loci have been identified linked to autism, which may contribute to the phenotype, such as: AUTS1 on chromosome 7q22, AUTS3 on chromosome 13q14, AUTS4 on chromosome 15q11, AUTS5 on chromosome 2q, and others. Two of the genes strongly linked to autism are: the EN2 gene, which encodes a protein involved in the development of the cerebellum; and the SLC6A4 gene, which encodes a serotonin transporter.
Farag et al. (1993) conducted a clinicogenetic assessment of 400 institutionalized mentally retarded (IQ less than 50) Kuwaiti patients during a 4-year period (1986-1990). One of the patients was found to be suffering from autism.
Al-Salehi et al., (2009) described 49 autistic patients (37 males and 12 females) with a mean age of 6.3 years. Five of the patients didn’t have any speech, and another five patients had a history of regression of language around the age of 18-24 months. The onset of symptoms in 42 patients was before the age of 3-years. In addition, two other patients had their onset of symptoms probably before 3-years of age. Of the 49 patients, 44 were diagnosed with autism, and 5 with Pervasive Developmental Disorder-Not Otherwise Specified (PDDNOS). Out of all patients, 11 had seizures, 27 had mental retardation, 22 had extreme hyperactivity, 2 had G6PD deficiency, one had Tourette syndrome, and one had cerebral palsy. Twenty five patients were taking psychotropic medications; some of them received more than one medication. Parental consanguinity was found in 14 patients. Two patients had siblings with autism, and one had a sibling with Down syndrome. Chromosomal analysis was performed in 19 patients; one of them was found to have a duplication of the long arm of chromosome 9.
In a study of the prevalence of autism in children born to Somali parents living in Sweden, Barnevik-Olsson et al. (2008) reviewed the records of 17 children (13 males, four females), born between 1988 and 1998 (age range 7-17 years) and with a Somali background, who had a diagnosis of autistic disorder or pervasive developmental disorder not otherwise specified (PDDNOS). The prevalence of autistic disorder or PDDNOS was found to be three to four times higher than in the non-Somali group (0.7% vs 0.19%).
Two years later, Barnevik-Olsson et al. (2010) conducted a follow-up study (birth years 1999-2003) of the prevalence of autism in children of Somali background living in the county of Stockholm. The prevalence of autism and PDDNOS (with learning disability) was 0.98% (18/1836) in the Somali group and 0.21% (232/111555) in the group of children of non-Somali origin (p<0.001). The increased prevalence remained since their earlier study in year 2008 and became four and five times higher in children of Somali background. A clinical observation was that more than 80%, in addition to autism and learning disability, had a profound hyperactivity. The findings accord with many other studies reporting higher prevalence rates of autism in children of immigrant mothers.