Tatton‐Brown–Rahman syndrome (TBRS) or DNMT3A‐overgrowth syndrome is characterized by overgrowth and intellectual disability associated with minor dysmorphic features, obesity, and behavioral ...problems. It is caused by variants of the DNMT3A gene. We report four patients with this syndrome due to de novo DNMT3A pathogenic variants, contributing to a deeper understanding of the genetic basis and pathophysiology of this autosomal dominant syndrome. Clinical and magnetic resonance imaging assessments were also performed. All patients showed corpus callosum anomalies, small posterior fossa, and a deep left Sylvian fissure; as well as asymmetry of the uncinate and arcuate fascicles and marked increased cortical thickness. These results suggest that structural neuroimaging anomalies have been previously overlooked, where corpus callosum and brain tract alterations might be unrecognized neuroimaging traits of TBRS syndrome caused by DNMT3A variants.
ANO3 and early-onset dyskinetic encephalopathy Jiménez de Domingo, Ana; Lopez-Martín, Sara; Albert, Jacobo ...
European journal of medical genetics,
December 2020, 2020-Dec, 2020-12-00, 20201201, Volume:
63, Issue:
12
Journal Article
Peer reviewed
Mutations in the ANO3 gene have been associated with autosomal dominant craniocervical dystonia. However, little else is known about the genotype-phenotype characteristics of this disorder. Here we ...describe a 3 years-old girl with distal myoclonic dystonia. Whole exome sequencing in trio revealed a de novo missense ANO3 variant not previously described in international databases. A global psychomotor regression was observed once dystonia was present. Brain MRI changes paralleled these findings: whereas MRI at the age of 18 months was normal, mild brain and cerebellar atrophy was observed 18 months later. These results suggest that missense mutations in ANO3 may underlie complex disorders particularly characterized by early psychomotor regression and dystonia.
Bi-allelic mutations in the TUBGCP4 gene have been recently associated with autosomal recessive microcephaly with chorioretinopathy. However, little is known about the genotype-phenotype ...characteristics of this disorder. Here, we describe a 5-year-old male patient with autism and a normal occipitofrontal circumference. No retinal abnormalities were observed. Brain MRI revealed the presence of enlarged sheaths of both tortuous optic nerves; both eyes had shorter axial lengths. Whole-exome sequencing in trio revealed synonymous TUBGCP4 variants in homozygous state: c.1746G>T; p.Leu582=. This synonymous variant has been previously described and probably leads to skipping of exon 16 of TUBGCP4. These results broaden the clinical spectrum of this new syndrome and suggest that TUBGCP4 bi-allelic mutations may underlie complex neurodevelopmental disorders.
Abstract Fetal alcohol syndrome represents the classic and most severe manifestation of epigenetic changes induced by exposure to alcohol during pregnancy. Often these patients develop attention ...deficit hyperactivity disorder. We analyzed cortical thickness in 20 children and adolescents with fetal alcohol syndrome and attention deficit hyperactivity disorder (group 1), in 20 patients without fetal alcohol syndrome (group 2), and in 20 control cases. The first group revealed total cortical thickness significantly superior to those of the other two groups. In per-lobe analyses of cortical thickness, group 1 demonstrated greater cortical thickness in the frontal, occipital, and right temporal and left frontal lobes compared with the second group, and in both temporal lobes and the right frontal lobe compared with the control group. This study demonstrated greater cortical thickness in patients with attention deficit hyperactivity disorder and heavy prenatal exposure to alcohol, probably as an expression of immature or abnormal brain development.
Autism spectrum disorder (ASD) is a group of neurological and developmental disabilities characterised by clinical and genetic heterogeneity. The current study aimed to expand ASD genotyping by ...investigating potential associations with
mutations. Specifically, the disease-causing variants of
in 410 trios manifesting neurodevelopmental disorders using whole-exome sequencing were explored. The consequences of the identified variants were studied at the transcript level using quantitative polymerase chain reaction (qPCR). For validation, immunofluorescence and immunoblotting were performed to analyse mutational effects at the protein level. The compound heterozygous variants of
(NM_182914.3:c.2483T>G; p.(Val828Gly) and NM_182914.3:c.2362G>A; p.(Glu788Lys)) were identified in a 4.5-year-old male, clinically diagnosed with autism spectrum disorder, developmental delay and intellectual disability. Both variants reside within the nesprin-2 giant spectrin repeat (SR5) domain and are predicted to be highly damaging using in silico tools. Specifically, a significant reduction of nesprin-2 giant protein levels is revealed in patient cells.
transcription and the nuclear envelope localisation of the mutant proteins was however unaffected as compared to parental control cells. Collectively, these data provide novel insights into the cardinal role of the nesprin-2 giant in neurodevelopment and suggest that the biallelic hypomorphic
mutations may be a new cause of intellectual disability and ASD.
Attention-deficit/hyperactivity disorder (ADHD) is a complex and heterogeneous neurodevelopmental disorder from a causal, clinical and prognostic perspective. Research reflects its multifactorial ...nature with a prominent role of genetic factors. Population studies have historically pointed to the involvement of numerous genetic variants of small effect size, which hardly by themselves increase the risk of presenting the disorder and hardly justify its high heritability. Many of them are present in more than 60% of the general population, suggesting their modulatory rather than causal role. However, after the irruption of new genetic techniques in the last 15 years, a greater number of cases are being identified with genetic disorders (many of them monogenic), whose genetic variants alone explain the presence of ADHD. A detailed study of the personal and family history, as well as a complete physical examination, can help to identify some of them. The identification of the cause in this group of cases has a crucial value in clinical counseling, genetic-familial counseling and prognostic anticipation, as well as in the performance or avoidance of complementary studies and in the design of the intervention plan.
. COL18A1 gene mutations have been associated with Knobloch syndrome, which is characterized by ocular and brain abnormalities. Here we report a 4.5 years-old male child with autism and two ...novel COL18A1 mutations (NM_030582.4: c.1883_1891dup and c.1787C>T). Hypermetropic astigmatism, but not brain migration disorders, was observed. However, an asymmetric pattern of cerebellar perfusion and a smaller arcuate fascicle were found. Low levels of collagen XVIII were also observed in the patient´s serum. Thus, biallelic loss-of-function mutations in COL18A1 may be a new cause of autism without the brain malformations typically reported in patients with Knobloch syndrome.
Abstract Structural and functional brain studies on attention deficit/hyperactivity disorder (ADHD) have primarily examined anatomical abnormalities in the prefronto-striatal circuitry (especially, ...dorsal and lateral areas of the prefrontal cortex and dorsal striatum). There is, however, increased evidence that several temporal lobe regions could play an important role in ADHD. The present study used MRI-based measurements of cortical thickness to examine possible differences in both prefrontal and temporal lobe regions between medication-näive patients with ADHD ( N =50) and age- and sex-matched typically developing controls ( N =50). Subjects with ADHD exhibited significantly decreased cortical thickness in the right temporal pole and orbitofrontal cortex (OFC) relative to healthy comparison subjects. These differences remained significant after controlling for confounding effects of age, overall mean cortical thickness and comorbid externalizing conditions, such as oppositional defiant and conduct disorders. These results point to the involvement of the temporal pole and OFC in the neuropathology of ADHD. Moreover, present findings add evidence to the assumption that multiple brain regions and psychological processes are associated with ADHD.
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