Previous studies revealed that psychiatric disorders are more common among relatives of children with ASD [9, 30, 39], whereas there are few studies that had included autistic traits in psychiatric disorders like schizophrenia. Meanwhile, our study focused on the prevalence of autistic traits among children of schizophrenic parents, comparing them with children of non-psychiatric parents, and thus our study is considered novel in Egypt.
Genetic overlap between ASD and schizophrenia has been proved by recent studies , where both of them are highly heritable disorders, with schizophrenia having a 25–33% genetic contribution and ASD having a 49% genetic contribution. Both disorders have hereditary influences that lead to impaired social contact, but their genetic associations have distinct developmental profiles that relate to their clinical onset and symptoms .
Furthermore, new research indicates that changes in gene expression regulation, synaptic architecture and function, and immunity are all important cellular mechanisms in both conditions . Besides that, growing evidence indicates that complex gene-environment interactions play a role in both disorders .
In the current study, we found that the prevalence of autistic traits among the children of schizophrenic parents is 47.2%, who scored above the cutoff point on the AQ-Child Questionnaire and 19.4% of children of healthy parents.
In agreement with our study, studies revealed that the presence of schizophrenia in the parents or other mental disorder increases the risk of autistic traits or autism in their children; Salah El-Deen and Mahdy  found that the prevalence of autistic traits among the children of schizophrenic patients is 44.4% who scored above the cutoff point on AQ-Child Questionnaire. Also, Sullivan et al.  found in a Swedish and a Stockholm County cohort study that the presence of schizophrenia in parents was accompanied by an increased risk for ASD; it was approximately three times higher in those whose parents suffered from schizophrenia. Moreover, Larsson et al.  studied the relationship between the psychiatric history of the parents, and the autism risk in their children and detected a markedly increased risk for autism in the offspring of parents with a psychiatric history of schizophrenia or mood disorder.
Other studies asserted that ASD children are a risk factor to their parents to have schizophrenia or other mental disorder; schizophrenia spectrum disorders are more common among parents who have an autistic child . Also, Daniels et al.  stated that parents of autistic children were more borne to be hospitalized for a mental disorder than parents of control children. Schizophrenia among both the mothers and the fathers was associated with autism in their children with odds ratio 1.9 and 2.1, respectively. There are common genetic factors shared between ASD and schizophrenia [10, 13].
This is consistent with the results of the current study where the presence of schizophrenia in either mother or the father increases the autism risk in the offspring. First, regarding the impact of schizophrenia in the parents on the ASD outcome, it is clear from this study that the presence of schizophrenia in the mother or the father increases the autism risk in the offspring and this is positively correlated with the result of our study. Second, this study showed that schizophrenia in both mothers and fathers increased the ASD risk in the offspring.
In contrast, Posserud et al.  confirmed that the frequency of children with high scores above the cutoff point on the Autism Spectrum Screening Questionnaire (ASSQ) was about 2.7% in the general population of children aged 7–9 years, and this difference may be due to the use of a different questionnaire. Another possible cause for our findings is that we used a self-report questionnaire, such as the AQ, which may not be reliable in clinical assessments, also it may be attributed to that in the last few years, the overuse of electronic games, videogames, and another modern way of technology, which lead to symptoms like autistic traits (prefer to be alone, have weak social skills, have problems in coping easily in social situations, are not eager to communicate and speak in public).
In this study, there was no statistically significant relationship between the prevalence of autistic traits and the sex of children in both groups.
In agreement with our results, two studies included their participants who are children with one schizophrenic parent; one of them found that the risk of ASD outcome was not correlated to the sex of the child  and the other one reported that there was no statistical significant association between gender of the children of schizophrenic patients and their AQ scores .
Other studies carried on autistic children of non-psychiatric parents found that there was no correlation between the severity of autistic symptoms and the sex of children [28, 40]. Some found that there were no gender differences in autistic symptoms but the daily living skills functioning was better in females .
In contrast with our study, Allison et al.  stated that there was a significant difference as regard sex, by higher scoring of boys than girls on the quantitative version of the Checklist for Autism in Toddlers (Q-CHAT). This finding proposed that boys may exhibit more difficulties in social communication and rigid repetitive behaviors than girls in the stage of early development.
Ruzich et al.  also found a mild impact of sex on AQ in their study, with males scoring an average of 2.5 points higher than females.
In another study measuring autistic characteristics in the general population, it was observed that males had higher AQ scores than females . The previous results are inconsistent with our study but may be due to our small sample size and methodological differences, in addition to the absence of a family history of psychiatric disorders in the selected probands.
Russell et al.  found a clear gender bias as regards autistic features with boys having a greater proportion of autistic features than girls, whether or not diagnosed. Rutter  stated that boys have ASD four times more than girls. Holtmann et al.  also revealed significant gender difference but this time there is more symptoms in females than males, particularly social problems, attention problems, and thought problems.
Regarding the age of parents
This study found no significant relationship between the severity of autistic traits in children and the age of parents in both case and control groups.
In agreement with our study, Salah El-Deen and Mahdy  reported that there was no statistical difference in age of schizophrenic parents and risk of autistic traits in their offspring. Other studies carried on children of ono-psychiatric parents also found no significant association between the age of the parents and risk of autism [29, 33].
In contrast to our study, many studies confirmed the strong correlation between the increased risk of having ASD in the children and the age of the parent [24, 38] or the age of mothers  or the increase in the order of the childbirth.
Reichenberg et al.  asserted that the risk of ASD increases about 6 times in offspring of men 40 years or older when they are compared with those of men younger than 30 years. Also, another study stated that every 10 years increase in the age of mothers or fathers increases the risk of ASDs in their children (1.3 and 1.28 folds, respectively) .
The discrepancy with our results may be because of the small sample size and methodological difference; also, we studied autistic traits not autism on offspring of schizophrenia parents.
Regarding socioeconomic status
In our study, there was no significant statistical difference regarding the relationship between the severity of autistic traits in the children and the socioeconomic status of the schizophrenic parent except in insufficient income and low social class were more associated with AQ-Child score; also, there was no statistical association between socioeconomic status and AQ-Child score among the control group.
In agreement with our study, Kelly et al.  found that income status of mothers had a strong association with the likelihood of a child having a diagnosis of autism in their primary care records. Ayoub et al.  also mentioned in their study results that the prevalence of ASD with associated intellectual disability (ID) was higher in areas with the highest level of deprivation and the highest percentage of unemployed adults, single-parent families, and persons with no diploma. Rai et al.  in their study mentioned that lower socioeconomic status was associated with an increased risk of ASD. Also, Malhotra et al.  found a significant association between autism and families coming from the upper socioeconomic status. That was contributed to the availability of health care services for those families.
In contrast, some studies stated that no statistically significant association between the risk of autism and socioeconomic status [6, 33]. Others found that maternal socioeconomic class did not significantly associate with having an ASD diagnosis nor displaying severe autistic traits .
The inconsistency of these results to ours may be due to these studies not comparing between healthy and schizophrenic parents as in our study; also, the difference may be due to the parents in our case group having a serious mental illness unlike parents of those studies who did not suffer from any mental illness.
Regarding education and occupation of the parents
In this study, there was no significant statistical difference regarding the relationship between the severity of autistic traits in the children and the education and the occupation of their parents in the case and control group.
In agreement with our study, Salah El-Deen and Mahdy  reported that there was no statistical difference relation between the severity of autistic traits in the children and the education and the occupation of schizophrenic parents. Other studies that carried on ASD children of non-psychiatric parents revealed that the risk of ASD was not associated with education or occupation of the parents [6, 42] or maternal education .
On the other hand, Rai et al.  mentioned in their study that children of parents with manual occupations were at higher risk of ASD. This is inconsistent with the results of our study maybe because of the cultural differences and this study was applied in Sweden, a country that has routine screening for developmental problems, free universal healthcare, and thorough protocols for diagnoses of autism.
Regarding correlation of illness duration of schizophrenic parents and autism quotient (AQ) scores of their offspring
In this study, there is a weak positive correlation between duration of illness of schizophrenic parents and AQ meaning AQ scores will increase when the duration of schizophrenia illness increase but this correlation is with no statistical significance (Table 7). This non-significance may be due to the small sample size of our study this point can be overcome in the future research. Unfortunately, we did not find any study that approached this point of correlation.