in this review , pubmed and sciencedirect databases were used to identify relevant articles published until the 3rd of april 2013 ( date of search ) . the search was conducted using the electronic library of king saud bin abdul aziz university for health sciences , riyadh , saudi arabia . pubmed search identified 3 groups of articles as follows : disease of interest ( keyword : autism ) , geographical location ( keywords : saudi , uae , oman , kuwait , qatar , and bahrain ) , and epidemiological terms ( keywords : epidemiology , prognosis , diagnosis , pattern , odds , risk , incidence , prevalence , impact , trends , and biomarker ) . finally , the boolean operator and combined the results for each group of articles , a total of 22 articles met the inclusion criteria . epidemiology of autism  and each of the gcc countries individually , which yielded a total of 79 results . the titles of the final list consisting of 101 results were reviewed , 85 articles were excluded because they were not related to epidemiology of autism , and the abstracts of the remaining 16 articles were obtained . after reviewing the 16 abstracts , 6 more articles were eliminated : reviews ( n=3 ) , 2 were qualitative studies and abstract / full text of the sixth was irretrievable . a search was conducted for the full text of the remaining 10 articles , of which 8 were located and 2 were not . the first was an article published as a brief communication,16 and the second is an article published during the writing up of this review.17 literature search flowchart . studies were identified from 3 gcc countries only ; oman , saudi arabia , and uae . the 10 included articles , 3 were prevalence studies , and the rest discussed potential risk factors or biomarkers for autism in patients from gcc countries . prevalence studies were conducted in uae,18 saudi arabia,19 oman,20 and bahrain.17 the prevalence of asd was 1.4 per 10,000 in oman , and 29 per 10,000 for pdd in uae , and 4.3 per 10,000 in bahrain.17,18,20 the saudi study documented patients characteristics and reasons for referral for group of saudi autistic patients.19 male gender and history of developmental delay were significantly associated with autism prevalence in all 3 studies . consanguinity was present in 28.6% of saudi patients , and behavioral problems such as hyperactivity or aggression were evident in 45% of patients ( table 1).19 summary of epidemiological studies on autism / autism spectrum disorder in the gulf cooperation countries . the included studies were conducted in saudi arabia , oman , or bahrain , and all employed the case - control study design . sample size varied between these studies from 52 to 204 patients ; and the risk factors investigated were : suboptimal breastfeeding,21 lead exposure,22 serum osteopontin,23 maternal and paternal age , cesarian section , and prenatal complications . delayed initiation of breastfeeding and no colostrum intake was associated with increased risk of asd . exclusive and prolonged breastfeeding ( up to 24 months or more ) markedly reduced the risk of developing asd.21 higher blood levels of lead22 and osteopontin23 were found in autism patients . occurrence of autistic disorder was correlated with maternal ( or 1.83 ) and paternal ( or 2.08 ) age above 30 years at time of birth . the disease was also more common among children of mothers who delivered with a cesarian section or had antenatal complications16,17 ( table 1 ) . lipid peroxidation,24 glutathione peroxidase,25 superoxide dismutase , sodium - potassium adenosine triphosphatase,21 lactate , saturated fatty acids,26 and homocysteine26 levels were significantly higher among autistic patients . inversely , levels of vitamin e,24 glutathione,24 folate , vitamin b12,27 and some polyunsaturated acids were much lower in autistic patients . serum osteopontin levels were higher among autistic patients,25 and levels were positively related to the severity of autism ( table 1 ) . prevalence studies were conducted in uae,18 saudi arabia,19 oman,20 and bahrain.17 the prevalence of asd was 1.4 per 10,000 in oman , and 29 per 10,000 for pdd in uae , and 4.3 per 10,000 in bahrain.17,18,20 the saudi study documented patients characteristics and reasons for referral for group of saudi autistic patients.19 male gender and history of developmental delay were significantly associated with autism prevalence in all 3 studies . consanguinity was present in 28.6% of saudi patients , and behavioral problems such as hyperactivity or aggression were evident in 45% of patients ( table 1).19 summary of epidemiological studies on autism / autism spectrum disorder in the gulf cooperation countries . the included studies were conducted in saudi arabia , oman , or bahrain , and all employed the case - control study design . sample size varied between these studies from 52 to 204 patients ; and the risk factors investigated were : suboptimal breastfeeding,21 lead exposure,22 serum osteopontin,23 maternal and paternal age , cesarian section , and prenatal complications . delayed initiation of breastfeeding and no colostrum intake was associated with increased risk of asd . exclusive and prolonged breastfeeding ( up to 24 months or more ) markedly reduced the risk of developing asd.21 higher blood levels of lead22 and osteopontin23 were found in autism patients . occurrence of autistic disorder was correlated with maternal ( or 1.83 ) and paternal ( or 2.08 ) age above 30 years at time of birth . the disease was also more common among children of mothers who delivered with a cesarian section or had antenatal complications16,17 ( table 1 ) . lipid peroxidation,24 glutathione peroxidase,25 superoxide dismutase , sodium - potassium adenosine triphosphatase,21 lactate , saturated fatty acids,26 and homocysteine26 levels were significantly higher among autistic patients . inversely , levels of vitamin e,24 glutathione,24 folate , vitamin b12,27 and some polyunsaturated acids were much lower in autistic patients . serum osteopontin levels were higher among autistic patients,25 and levels were positively related to the severity of autism ( table 1 ) . the prevalence of asd and pdd was highly variable between included studies.18,20 the difference between both rates could be attributed , in part , to setting , method of assessment , and age of participants . the omani study20 included a larger sample with wide age range to determine prevalence of formally diagnosed asd from medical records . conversely , the emirati study18 screened a sample of preschool children for undiagnosed pdd , and the case definition for pdd is more inclusive than asd . for example , studies in europe recorded a prevalence that ranged from 1.9 up to 72.6 per 10,000 , and the range has been wider ( 2.8 - 94 per 10,000 ) in china.1 prevalence is also affected by accessibility to a specialized autism care center and source of case identification ( mainly families ) . a low prevalence rate is expected in areas with no facilities or centers for case reporting . over time , healthcare professionals and families have learned more about the disorder , and the increased awareness resulted in more comprehensive diagnostic criteria . this emphasizes the need to establish a reliable autism - screening tool that can be applied in community - based studies to produce more precise prevalence in gcc countries . collaborative efforts should target increasing awareness of the community toward asd to encourage early consultation and diagnosis . also , availability and accessibility to diagnosis and treatment centers should be assessed in light of the burden of this disorder . the male to female ratio in gcc countries was consistent with studies from elsewhere showing male predilection,1 and there is no evidence to date that explains this finding.12 one possible reason is that female children are more able to mask their behavioral difficulties than males.19 moreover , culture in developing countries may be a contributing factor , as some families may pay more attention to the development of male children compared with females . as the burden of reporting cases falls on parents ; there could be a lack of detection or lack of willingness to report certain behavior exhibited by a female child . this cultural perception could explain the older age for females at autism diagnosis in saudi arabia.19 either way ; more research is needed to explain other reasons behind this significant gender difference . still , with consanguinity rates in saudi arabia that range from 34 - 80% , depending on rural , or urban setting , this risk factor deserves further investigation.19,28 lead toxicity has been associated with autism,22 which is in agreement with other research.29 however , the nature of environmental exposure that might have contributed to lead toxicity was not clarified in the study . a strong dose - response protective effect of breastfeeding21 is in agreement with other studies,30,31 but potential for recall bias remains high as data collection depends on parents memory and reporting . findings for various biomarkers were comparable with studies carried out elsewhere.29,32 - 35 still , more research is needed to clarify applicability of these biomarkers for early screening or monitoring of autistic patients . first , is the sample size , as numbers of cases and controls used were small and can not be considered representative . also , the recruitment of cases and controls was from specialized clinics / tertiary care institutions , which might be problematic when extrapolating results to community autistic children in gcc countries . second , is that cases were recruited from pediatric wards , and none come from psychiatric clinics . the diagnosis of autism must include more comprehensive behavioral / psychological considerations to form a full picture about the disorder . the current study s limitations were the small number of studies identified and absence of studies from 3 gcc countries , which precluded comparing prevalence of autism across countries . generally , there is an evident lack of research into risk factors affecting the etiology of autism in gcc countries . consanguinity , multiparity , and closely - spaced pregnancies are common in the gcc region , and provide an exceptional opportunity to learn more about genetic determinants of the disease . also , dietary habits should be looked into as they could help in i ) investigating the risk and prognostic factors of the disease and , ii ) assisting families by identifying high - risk foods that could affect their children . more focus should be given to children in psychiatric wards to identify autistic symptoms among them . in conclusion , population - based studies should focus on quantifying the burden of asd in gcc countries . knowing the burden and extent of disease could help design screening tools that are applicable , culturally acceptable , and cost - effective to identify individuals who can benefit the most from early diagnosis and intervention . furthermore , raising asd awareness among parents , preschool / elementary school teachers are invaluable in helping autistic children cope with different challenges . generally , there is an evident lack of research into risk factors affecting the etiology of autism in gcc countries . consanguinity , multiparity , and closely - spaced pregnancies are common in the gcc region , and provide an exceptional opportunity to learn more about genetic determinants of the disease . also , dietary habits should be looked into as they could help in i ) investigating the risk and prognostic factors of the disease and , ii ) assisting families by identifying high - risk foods that could affect their children . more focus should be given to children in psychiatric wards to identify autistic symptoms among them . in conclusion , population - based studies should focus on quantifying the burden of asd in gcc countries . knowing the burden and extent of disease could help design screening tools that are applicable , culturally acceptable , and cost - effective to identify individuals who can benefit the most from early diagnosis and intervention . furthermore , raising asd awareness among parents , preschool / elementary school teachers are invaluable in helping autistic children cope with different challenges .
objective : to assess the current state of knowledge on the epidemiology of autism in arab gulf countries , and identify gaps for future research.methods:pubmed and sciencedirect databases were used to identify relevant articles published until the 3rd of april 2013 ( date of search ) . 
 the search was conducted using the electronic library of king saud bin abdulaziz university for health sciences , riyadh , saudi arabia . 
 studies were eligible for inclusion if they concerned the epidemiology of autism , conducted in any arab gulf country , and published in english.results:twelve articles met the inclusion criteria . 
 studies showed a prevalence ranging from 1.4 to 29 per 10,000 persons . 
 identified risk factors were metabolic , autoimmune , and environmental in nature . 
 the following determinants were found as possible contributing factors for autism : suboptimal breast - feeding , advanced maternal and paternal age , cesarean section , and prenatal complications.conclusion:only a few studies explored the epidemiology of autism in arab gulf countries and none have investigated the burden of the disease on the child , family , or society . more research is needed to better identify the burden and risk factors of autism in gulf countries .