Genomic analysis of 116 autism families strengthens known risk genes and highlights promising candidates.

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with a strong genetic component in which rare variants contribute significantly to risk. We performed whole genome and/or exome sequencing (WGS and WES) and SNP-array analysis to identify both rare sequence and copy number variants (SNVs and CNVs) in 435 individuals from 116 ASD families. We identified 37 rare potentially damaging de novo SNVs (pdSNVs) in the cases (n = 144). Interestingly, two of them (one stop-gain and one missense variant) occurred in the same gene, BRSK2. Moreover, the identification of 8 severe de novo pdSNVs in genes not previously implicated in ASD (AGPAT3, IRX5, MGAT5B, RAB8B, RAP1A, RASAL2, SLC9A1, YME1L1) highlighted promising candidates. Potentially damaging CNVs (pdCNVs) provided support to the involvement of inherited variants in PHF3, NEGR1, TIAM1 and HOMER1 in neurodevelopmental disorders (NDD), although mostly acting as susceptibility factors with incomplete penetrance. Interpretation of identified pdSNVs/pdCNVs according to the ACMG guidelines led to a molecular diagnosis in 19/144 cases, although this figure represents a lower limit and is expected to increase thanks to further clarification of the role of likely pathogenic variants in ASD/NDD candidate genes not yet established. In conclusion, our study highlights promising ASD candidate genes and contributes to characterize the allelic diversity, mode of inheritance and phenotypic impact of de novo and inherited risk variants in ASD/NDD genes.

Dissecting the multifaceted contribution of the mitochondrial genome to autism spectrum disorder.

Autism spectrum disorder (ASD) is a clinically heterogeneous class of neurodevelopmental conditions with a strong, albeit complex, genetic basis. The genetic architecture of ASD includes different genetic models, from monogenic transmission at one end, to polygenic risk given by thousands of common variants with small effects at the other end. The mitochondrial DNA (mtDNA) was also proposed as a genetic modifier for ASD, mostly focusing on maternal mtDNA, since the paternal mitogenome is not transmitted to offspring. We extensively studied the potential contribution of mtDNA in ASD pathogenesis and risk through deep next generation sequencing and quantitative PCR in a cohort of 98 families. While the maternally-inherited mtDNA did not seem to predispose to ASD, neither for haplogroups nor for the presence of pathogenic mutations, an unexpected influence of paternal mtDNA, apparently centered on haplogroup U, came from the Italian families extrapolated from the test cohort (n = 74) when compared to the control population. However, this result was not replicated in an independent Italian cohort of 127 families and it is likely due to the elevated paternal age at time of conception. In addition, ASD probands showed a reduced mtDNA content when compared to their unaffected siblings. Multivariable regression analyses indicated that variants with 15%-5% heteroplasmy in probands are associated to a greater severity of ASD based on ADOS-2 criteria, whereas paternal super-haplogroups H and JT were associated with milder phenotypes. In conclusion, our results suggest that the mtDNA impacts on ASD, significantly modifying the phenotypic expression in the Italian population. The unexpected finding of protection induced by paternal mitogenome in term of severity may derive from a role of mtDNA in influencing the accumulation of nuclear de novo mutations or epigenetic alterations in fathers' germinal cells, affecting the neurodevelopment in the offspring. This result remains preliminary and needs further confirmation in independent cohorts of larger size. If confirmed, it potentially opens a different perspective on how paternal non-inherited mtDNA may predispose or modulate other complex diseases.

Electroencephalographic findings in ATRX syndrome: A new case series and review of literature.

Alpha-thalassemia X-linked intellectual disability syndrome (ATRX) is a rare genetic condition caused by mutations in the ATRX gene characterized by distinctive dysmorphic features, alpha thalassemia, mild-to-profound intellectual disability, and epilepsy, reported in nearly 30% of the patients. To date, different types of seizures are reported in patients with ATRX syndrome including either clonic, tonic, myoclonic seizures or myoclonic absences. However, an accurate analysis of electroencephalographic features is lacking in literature. We report on the epileptic and electroencephalographic phenotype of seven unpublished patients with ATRX syndrome, highlighting the presence of a peculiar EEG pattern characterized by diffuse background slowing with superimposed low voltage fast activity. Likewise, we also review the available literature on this topic.

Contribution of CACNA1H Variants in Autism Spectrum Disorder Susceptibility.

Autism Spectrum Disorder (ASD) is a highly heterogeneous neuropsychiatric disorder with a strong genetic component. The genetic architecture is complex, consisting of a combination of common low-risk and more penetrant rare variants. Voltage-gated calcium channels (VGCCs or Cav) genes have been implicated as high-confidence susceptibility genes for ASD, in accordance with the relevant role of calcium signaling in neuronal function. In order to further investigate the involvement of VGCCs rare variants in ASD susceptibility, we performed whole genome sequencing analysis in a cohort of 105 families, composed of 124 ASD individuals, 210 parents and 58 unaffected siblings. We identified 53 rare inherited damaging variants in Cav genes, including genes coding for the principal subunit and genes coding for the auxiliary subunits, in 40 ASD families. Interestingly, biallelic rare damaging missense variants were detected in the CACNA1H gene, coding for the T-type Cav3.2 channel, in ASD probands from two different families. Thus, to clarify the role of these CACNA1H variants on calcium channel activity we performed electrophysiological analysis using whole-cell patch clamp technology. Three out of four tested variants were shown to mildly affect Cav3.2 channel current density and activation properties, possibly leading to a dysregulation of intracellular Ca2+ ions homeostasis, thus altering calcium-dependent neuronal processes and contributing to ASD etiology in these families. Our results provide further support for the role of CACNA1H in neurodevelopmental disorders and suggest that rare CACNA1H variants may be involved in ASD development, providing a high-risk genetic background.

Brain Magnetic Resonance Findings in 117 Children with Autism Spectrum Disorder under 5 Years Old.

We examined the potential benefits of neuroimaging measurements across the first 5 years of life in detecting early comorbid or etiological signs of autism spectrum disorder (ASD). In particular, we analyzed the prevalence of neuroradiologic findings in routine magnetic resonance imaging (MRI) scans of a group of 117 ASD children younger than 5 years old. These data were compared to those reported in typically developing (TD) children. MRI findings in children with ASD were analyzed in relation to their cognitive level, severity of autistic symptoms, and the presence of electroencephalogram (EEG) abnormalities. The MRI was rated abnormal in 55% of children with ASD with a significant prevalence in the high-functioning subgroup compared to TD children. We report significant incidental findings of mega cisterna magna, ventricular anomalies and abnormal white matter signal intensity in ASD without significant associations between these MRI findings and EEG features. Based on these results we discuss the role that brain MRI may play in the diagnostic procedure of ASD.

Neuropsychiatric phenotype in a child with pseudohypoparathyroidism.

Pseudohypoparathyroidism (PHP) is a rare heterogeneous genetic disease characterized by end-organ resistance to parathyroid hormone. In adulthood, heterogeneous neurological and psychiatric disorders have been reported which are associated with hypoparathyroidism in general and with PHP in particular, while for childhood, data are scanty. We report a case of a boy with PHP type 1b, in whom neurological signs at the onset prevailed, characterized by tic-like dyskinesias associated with a series of heterogeneous not well-defined neurological and behavioral features, describing the diagnostic work-up performed and the follow-up. We suggest that the diagnostic hypothesis of PHP might be considered when dealing with a child with tic-like dyskinesias, especially if associated with a series of heterogeneous not well-defined neurological and behavioral features. In these cases, treatment with calcitriol and calcium has to be started as soon as possible to achieve a prompt and persistent clinical improvement.

Is cognitive behavioural therapy an effective complement to antidepressants in adolescents? A meta-analysis.

Calati R, Pedrini L, Alighieri S, Alvarez MI, Desideri L, Durante D, Favero F, Iero L, Magnani G, Pericoli V, Polmonari A, Raggini R, Raimondi E, Riboni V, Scaduto MC, Serretti A, De Girolamo G. Is cognitive behavioural therapy an effective complement to antidepressants in adolescents? A meta-analysis. OBJECTIVE: Evidence on effectiveness of combined treatments versus antidepressants alone in adolescents consists on a few studies in both major depressive and anxiety disorders. A meta-analysis of randomised 12-week follow-up studies in which antidepressant treatment was compared to combined treatment consisting of the same antidepressant with cognitive behavioural therapy has been performed. METHODS: Data were entered into the Cochrane Collaboration Review Manager software and were analysed within a random effect framework. A quality assessment has been performed through Jadad Scale. RESULTS: Higher global functioning at the Children's Global Assessment Scale was found in the combined treatment group (p < 0.0001) as well as higher improvement at the Clinical Global Impressions Improvement Scale (p = 0.04). No benefit of combined treatment was found on depressive symptomatology at the Children's Depression Rating Scale - Revised. CONCLUSION: Combined treatment seems to be more effective than antidepressant alone on global functioning and general improvement in adolescents with major depressive and anxiety disorders.

Epilepsy and EEG paroxysmal abnormalities in autism spectrum disorders.

The occurrence of epilepsy in autism is variable; nevertheless, EEG paroxysmal abnormalities (PA) are frequently recorded in patients with autism, although the influence of epilepsy and/or EEG PA on the autistic regression has not been clarified yet. We examine a large sample of 345 inpatients with autism, divided into three groups: (1) patients without epilepsy and EEG PA; (2) patients with EEG PA but no seizures; (3) patients with epilepsy including febrile convulsions. The prevalence of epilepsy (24.9%) and EEG PA (45.5%) was higher than that reported in the general population. The significant differences among the three groups concerned autistic regression (comparison between groups 1 and 2, p<0.05; comparison between groups 1 and 3, p<0.01), cerebral lesions (comparison between groups 1 and 2, p<0.05; between groups 1 and 3, p<0.001), and symptomatic autism (comparison between groups 1 and 2 as much as comparison between groups 1 and 3, p<0.001), which were prevalent in groups 2 and 3; while severe/profound mental retardation was more frequent in group 3 compared to group 1 (p<0.01). Focal epilepsy (43.0%) and febrile convulsions (33.7%) were frequent in the third group with epilepsy. EEG PA were mainly localized in temporal and central areas (31.4%). Only 2.6% of patients had subcontinuous/continuous EEG PA during sleep. Seizures and EEG PA were not related to autistic regression. EEG PA occurred mainly in childhood, while epilepsy tended to occur (p<0.001) as age increased. The age at onset of seizures had two peaks: between 0 and 5 and between 10 and 15 years with no difference between idiopathic and symptomatic cases. In 58.5% of subjects aged > or = 20 years, epilepsy including febrile seizures occurred at some point of their lives, while cases with only EEG PA were less frequent (9.7%). The relationship among autism, EEG PA and epilepsy should be clarified and investigated. In autism, seizures and EEG PA could represent an epiphenomenon of a cerebral dysfunction independent of apparent lesions.

Methyl-CpG-binding protein 2 (MECP2) gene mutations in an Italian sample of patients with pervasive developmental disorder and mental retardation.

Methyl-CpG-binding protein 2 (MECP2) gene mutations have been identified in girls with Rett syndrome and in boys with heterogeneous neuropsychiatric disorders. Because of the limited or inconsistent data reported in literature, the role of methyl-CpG-binding protein 2 gene in the pathogenesis of mental retardation and pervasive developmental disorders needs further study. We scanned methyl-CpG-binding protein 2 gene in 99 Italian patients with pervasive developmental disorder or with nonsyndromal mental retardation. Four methyl-CpG-binding protein 2 gene mutations were found: 2 in 4 girls with Rett disorder, the others in 2 girls with mental retardation. The wide phenotypic spectrum and the variants of methyl-CpG-binding protein 2 gene, which may play an important role in gene regulation and neurodevelopment, justify the literature's interest particularly in girls.

Cerebellar hypoplasia, continuous spike-waves during sleep, and neuropsychological and behavioral disorders.

We describe 3 patients with different degrees of cerebellar hypoplasia and continuous spike-waves during sleep: the more extensive the cerebellar hypoplasia, the more compromised the neuropsychological abilities and behavior. Cerebellar hypoplasia is a risk factor for epilepsy and/or neuropsychological and psychiatric disorders. Epilepsy is also strongly associated with familial antecedents for seizures, as previously reported. The cerebellum is implicated in controlling epileptic seizures and in regulating motor, cognitive, and emotional functions with a topographic organization. The association between cerebellar hypoplasia and continuous spike-waves during sleep has never been reported. We suggest that continuous spike-waves during sleep may further compromise neuropsychological and behavioral features that are associated with cerebellar hypoplasia.

Epilepsy in patients with pervasive developmental disorder not otherwise specified.

Data on epilepsy in pervasive developmental disorder not otherwise specified are few and scanty. Seventy-seven patients with pervasive developmental disorder not otherwise specified were compared with 77 with autistic disorder, matched for age and sex. The 2 groups were divided into 3 subgroups each: A, without electroencephalography (EEG) paroxysmal abnormalities or epilepsy; B, with EEG paroxysmal abnormalities without epilepsy; and C, with epilepsy. Mild mental retardation (P < .01), pathological neurological examination (P < .05), cerebral lesions (P < .01), abnormal EEG background activity (P < .001), and associated genetic pathologies (P < .01) were more common in pervasive developmental disorder not otherwise specified. Familial antecedents for epilepsy prevailed in subgroup C (P < .01). Epilepsy occurred in 35.1% of patients with pervasive developmental disorder not otherwise specified, with no statistically significant difference compared with autistic disorder. The mean age of seizure onset was earlier (2 years 8 months) in pervasive developmental disorder not otherwise specified (P < .000). Seizure outcome was better in autistic disorder. Genetic diseases and cerebral lesions should be investigated in pervasive developmental disorder not otherwise specified to clarify the etiological and clinical features.

Epilepsy, intelligence, and psychiatric disorders in patients with cerebellar hypoplasia.

The cerebellum is involved in motor and cognitive functions and behavior. Its role in controlling epileptic seizures has been demonstrated in the literature. Genetic factors can enhance epilepsy susceptibility when the cerebellum is damaged. We examined the occurrence and features of epilepsy, intelligence, and psychiatric disorders in 28 patients with cerebellar hypoplasia. We compared patients with (10; 35.7%) and without (18; 64.3%) epilepsy. The statistical evaluation showed a significant prevalence of familial antecedents for seizures in patients with epilepsy (P < .01); cerebral associated lesions and type of cerebellar hypoplasia did not influence the occurrence of epilepsy, which was partial in 80% of cases. Profound mental retardation prevailed in patients with epilepsy (P < .05). Both mental retardation (75%) and pervasive developmental disorders (17.8%) prevailed in our cases with respect to the general population (P < .000). Cerebellar hypoplasia in our sample seems to be an important risk factor for the occurrence of epilepsy, mental retardation, and psychiatric disorders.