Clinical Phenotypes,Whole Genome Sequencing And Brain Magnetic Resonance Imaging Features Of Global Developmental Delay With And Without Autism

Global developmental delay(GDD)is defined as a developmental disability of children under 5 years of age,which refers to significant delays in two or more developmental domains,including gross or fine motor,speech/language,cognitive,social/personal,and activities of daily living.After growing up,many patients with GDD would demonstrate intellectual disability(ID)over 5 years old.Autism spectrum disorder(ASD),abbreviated as autism,is considered to be a neurodevelopmental disorder that can lead to severe social communication deficits,repetitive behaviors,and limited interests.Both of them are common and disabling neuro developmental disorders with unclear etiology.An early diagnosis and proper treatment may improve outcome.Comorbidities occur also quite commonly between GDD/ID and ASD.At present,there is a lack of objective indicators for diagnosis.Differential diagnosis of some children with poor developmental level is difficult.It is an important research direction to be realized that accurate diagnosis and treatment should be evidenced by combining phenotype,genotype and endophenotype.Previous studies have mostly explored the comorbidities of GDD/ID in children with ASD from the perspective of ASD.Our previous studies showed that 68.3%of children with ASD under 5 years of age have combined with GDD.Studies by the Centers for Disease Control and Prevention(CDC)in the United States showed that approximately one-third of8-year-old children with ASD have combined ID.In addition,several studies have also shown that even with intensive interventions,children with ASD and comorbid cognitive delays seemed to make only limited developmental progress over time.Few studies have explored the comorbidities and developmental characteristics of ASD in children with GDD/ID from the perspective of GDD/ID.Environmental-genetic interactions in the pathogenesis of GDD/ID and ASD,genetic factors play an important role.At present,the genetic factors of GDD/ID and ASD are mostly studied by chromosome microarray analysis and whole exon sequencing.Whole genome sequencing,which can cover coding regions and non-coding regions,has gradually been applied in GDD/ID and ASD,but there are few relevant reports in China.There are no studies on whether there are differences in whole genome sequencing results and the relationship between gene results and clinical phenotypes in GDD with or without ASD.More than one thousands of genetic mutations have been found in GDD/ID and ASD.But the recurrence rate of individual genes is low,gene functional enrichment studies suggest these genes function in the regulation of gene expression,neuron communication(including synaptic function).Many genes associated with brain excitation/inhibition balance.It is suggested that the change of brain excitation/inhibition balance may be the common mechanism of these two diseases.A number of studies have found changes in the volume of whole brain and local brain areas in children with ASD,and some studies have also been carried out in GDD/ID.Excitation/inhibition balance and the change of gray matter and white matter volume are important endophenotypes of GDD and ASD.Medial prefrontal cortex is an important brain region related to social and cognitive functions.The imbalance of excitation/inhibition in the medial prefrontal cortex of GDD and ASD has been found in animal experiments.The above changes were also found in the ASD population,while there are no relevant reports on whether there is an imbalance of excitation/inhibition in the medial prefrontal cortex in children with GDD,whether there are differences in the balance of excitation/inhibition in the medial prefrontal cortex,gray matter and white matter volume in GDD with or without ASD.Therefore,begining from discussing the problem of ASD co-occurring with GDD,we divided the subjects into two subgroups,GDD+ASD-and GDD+ASD+,and explored the relationship between phenotype,genotype and endophenotype of GDD with or without ASD from three aspects:clinical phenotype,whole genome sequencing(WGS),excitation/inhibition balance,gray and white matter volume in the medial prefrontal cortex.Part?Clinical features of global developmental delay with or without autism spectrum disorderObjective:By studying the developmental level of children with GDD and its accompanying autism symptoms,to explore the comorbidity rate of ASD in GDD and the differences in developmental characteristics of GDD with or without ASD.Methods:Clinical data of 494 children with GDD aged between 18 months and 60monthswereretrospectivelyanalyzed.Analyses were performed first for the whole sample and then subdivided into two subgroups(GDD~+ASD~-and GDD~+ASD~+)according to whether the GDD patient was with or without ASD.Symptoms of autism were evaluated by the Autism Behavior Checklist and the Childhood Autism Rating Scale.The Chinese version of the Griffiths Developmental Schedules was used to evaluate the level of children's mental development.Results:(1)Prevalence of ASD in children with GDD was 54.9%.(2)Developmental imbalance existed in children with GDD.Language ability and personal social ability were severe deficient,the remaining domains were moderately defective to normal(P<0.05).(3)GDD children with poorer developmental levels were more likely to have ASD symptoms.(4)GDD~+ASD~-group and GDD~+ASD~+group have some common points as well as differences in the developmental features.The language delay of children in both subgroups was the most obviously defected.In the GDD~+ASD~+group,the DQ of gross motor skills>performance>eye-hand coordination skills>personal-social ability(p<0.05).There were no significant differences among the DQ of gross motor skills,performance,eye-hand coordination skills and personal-social ability in GDD~+ASD~-group(p>0.05).(5)The GDD~+ASD~-group had better performance,language,eye-hand coordination,personal-social ability than those of the GDD~+ASD~+group,but the gross motor skills in GDD~+ASD~-group were worse(p<0.05).Conclusion:GDD children have a high proportion of comorbid ASD(59.4%).Developmental imbalance existed in children with GDD,language ability and personal social ability were severe deficient,the remaining domains were moderately defective to normal.GDD children with poorer developmental levels are more likely to have ASD symptoms.Developmental profiles in both GDD~+ASD~-children and GDD~+ASD~+children have common features but there are also differences.Part?Whole-genome sequencing results of total developmental delay with orwithout autism spectrum disorderObjective:Use whole genome sequencing to investigate whether GDD,GDD with or without ASD were different in genotype,and to explore the relationship between genotype and clinical phenotype.Methods:A total of 122 of the 494 children included in the first part of the study underwent genetic testing according to their parents'permission and were included in this study.The genotypes of GDD,GDD~+ASD~-and GDD~+ASD~+children and the correlation between genotypes and clinical phenotypes were investigated by whole genome sequencing(children)combined with whole exome sequencing(parents).Results:(1)The positive rate of WGS in GDD was 49.2%,67.4%in GDD~+ASD~-and38.2%in GDD~+ASD~+.The positive rate of GDD~+ASD~-was higher than that of GDD~+ASD~+(p<0.05).(2)There was no difference in de novo mutation rate and inheritable mutation between GDD~+ASD~-and GDD~+ASD~+groups(p>0.05).(3)The overall GDD and two subgroups had the highest rate of missense mutation,followed by frameshift mutation and nonsense mutation(p<0.05).The rate of missense mutation in GDD~+ASD~+group was higher than that in GDD~+ASD~-group(p<0.05).(4)Most of the mutate genes in GDD were related to expression regulation,followed by those related to neural communication(p<0.05).(5)In children with GDD,the proportion of females in the gene positive group was higher than that in the negative group,and the proportion of combided with epilepsy,microcephaly was higher,and gross motor,performance and total developmental quotient were significantly lower(p<0.05).The lower the gross motor ability,the higher the gene positive rate(p<0.05).Abnormal head circumference was a predictive risk factor for positive genetic results(p<0.05).In GDD~+ASD~-group,there was no difference in general data and developmental quotient between gene positive and negative groups(p>0.05).In GDD~+ASD~+group,the proportion of females and abnormal head circumference were higher in gene positive group(p<0.05),and the scores of developmental quotient,ABC and CARS were not significantly different from those in the negative group(p>0.05).(6)SHANK3 and DMD/BMD were common genes in the two subgroups.RYR1 was a suspected pathogenic gene of GDD~+ASD~+,1 female PLXNA3 gene mutation caused GDD~+ASD~+and 1mitochondrial TRNL1 3243A>T mutation induced GDD~+ASD~+were reported for the first time.(7)In the overall GDD and GDD~+ASD~+group,the gene positive rate of female was higher than that of male(p<0.05),and there was no difference in the gene positive rate of different genders in GDD~+ASD~-group(p>0.05).Conclusion:The positive rate of WGS in GDD is high,and the children with poor development level(gross motor ability),female or abnormal head circumference should be tested.GDD mutation genes were mainly related to expression regulation,and missense mutation was the most common.Genetic factors played a greater role in GDD~+ASD~-.GDD~+ASD~-and GDD~+ASD~+were different in gene mutation types,but there were no significant differences in gene function and clinical phenotype between positive and negative cases.RYR1 was a suspected pathogenic gene of GDD~+ASD~+,1 female PLXNA3 gene mutation caused GDD~+ASD~+and 1 mitochondrial TRNL1 3243A>T mutation induced GDD~+ASD~+were reported for the first time.Part?Excitation/inhibition balance,gray and white matter volume in GDD with and without autism spectrum DisorderObjective:To investigate the Excitation/inhibition balance,gray and matter volume characteristics of bilateral medial prefrontal cortex in children with GDD and GDD~+ASD~-,GDD~+ASD~+subgroups.Methods:A total of 64 of the 494 children included in the first part of the study were examined by brain magnetic resonance spectroscopy according to their parents'permission and were included in this study.The bilateral medial prefrontal cortex were selected as the region of interest,and the correlation between brain imaging changes and clinical phenotypes in children with GDD,GDD~+ASD~-and GDD~+ASD~+was investigated by magnetic resonance spectroscopy combined with voxel-based morphological measurements.Results:(1)There was no difference in the excitation/inhibition balance,white and gray matter volume of bilateral medial prefrontal cortex in GDD between different ages and genders(p>0.05).(2)The excitation/inhibition balance of bilateral medial prefrontal cortex was negatively correlated with personal-social,eye-hand coordination and global developmental quotient of GDD(p<0.05).The white matter volume of GDD children wasnegatively correlated with eye-hand coordination and global development quotient(p<0.05).There was no correlation between gray matter volume and GDD development level(p>0.05).(3)The gray matter volume in GDD~+ASD~-group was smaller than that in GDD~+ASD~+group(p<0.05),but there was no difference in white matter volume and excitation/inhibition balance(p>0.05).(4)Symptoms of autism in GDD~+ASD~+group were not associated with the excitation/inhibition balance and gray/white matter volume of bilateral medial prefrontal cortex.Conclusion:There was no difference in the excitation/inhibition balance,white and gray matter volume of bilateral medial prefrontal cortex in GDD between different ages and genders.Excitation/inhibition balance and white matter volume of bilateral medial prefrontal cortex are correlated with the developmental level of children with GDD,but not with autistic symptoms of children with GDD.Compared with GDD~+ASD~+group,the gray matter volume of bilateral medial prefrontal cortex was smaller in GDD~+ASD~-group,and there was no difference in excitation/inhibition balance and white matter volume.