The clinical phenotype of Koolen-de Vries syndrome in Turkish patients and literature review

Koolen-de Vries syndrome (KdVS) is a rare multisystemic disorder caused by a microdeletion on chromosome 17q21.31 including KANSL1 gene or intragenic pathogenic variants in KANSL1 gene. Here, we describe the clinical and genetic spectrum of eight Turkish children with KdVS due to a de novo 17q21.31 deletion, and report on several rare/new conditions. Eight patients from unrelated families aged between 17 months and 19 years enrolled in this study. All patients evaluated by a clinical geneticist, and the clinical diagnosis were confirmed by molecular karyotyping. KdVS patients had some common distinctive facial features. All patients had neuromotor retardation, and speech and language delay. Epilepsy, structural brain anomalies, ocular, ectodermal, and musculoskeletal findings, and friendly personality were remarkable in more than half of the patients. Hypertension, hypothyroidism, celiac disease, and postaxial polydactyly were among the rare/new conditions. Our study contributes to the clinical spectrum of patients with KdVS, while also provide a review by comparing them with previous cohort studies.

Prenatal ultrasound findings in Koolen-de Vries foetuses: Central nervous system anomalies are frequent markers of this syndrome

Objective

Prenatal diagnoses of microdeletion syndromes without ultrasound findings in the first and second trimester are always difficult. The objective of this study is to report the prenatal ultrasound findings in four foetuses diagnosed with 17q21.31 microdeletions (Koolen‐de Vries syndrome) using chromosomal microarrays (CMA).

Patients and Methods

We present four foetuses with 17q21.31 microdeletion. All showed CNS anomalies in the third trimester, three had ventriculomegaly, and one hypogenesis of corpus callosum at 31 weeks of pregnancy.

Results

Array‐SNPs and CGH‐array were performed on uncultured amniocytes and peripheral blood revealing a 17q21.31 microdeletion.

Conclusions

Prenatal CNS anomalies (mainly ventriculomegaly) at third trimester, in spite of isolate, should be considered a prenatal ultrasound marker of this syndrome. This kind of malformations raise the possibility of an underlying genetic conditions including 17q21.31 microdeletion; thus, CMA should be taken into consideration when offering prenatal genetic counselling.

Impact of polymorphic transposable elements on transcription in lymphoblastoid cell lines from public data

Background

Transposable elements (TEs) are DNA sequences able to mobilize themselves and to increase their copy-number in the host genome. In the past, they have been considered mainly selfish DNA without evident functions. Nevertheless, currently they are believed to have been extensively involved in the evolution of primate genomes, especially from a regulatory perspective. Due to their recent activity they are also one of the primary sources of structural variants (SVs) in the human genome. By taking advantage of sequencing technologies and bioinformatics tools, recent surveys uncovered specific TE structural variants (TEVs) that gave rise to polymorphisms in human populations. When combined with RNA-seq data this information provides the opportunity to study the potential impact of TEs on gene expression in human.

Results

In this work, we assessed the effects of the presence of specific TEs in cis on the expression of flanking genes by producing associations between polymorphic TEs and flanking gene expression levels in human lymphoblastoid cell lines. By using public data from the 1000 Genome Project and the Geuvadis consortium, we exploited an expression quantitative trait loci (eQTL) approach integrated with additional bioinformatics data mining analyses. We uncovered human loci enriched for common, less common and rare TEVs and identified 323 significant TEV-cis-eQTL associations. SINE-R/VNTR/Alus (SVAs) resulted the TE class with the strongest effects on gene expression. We also unveiled differential functional enrichments on genes associated to TEVs, genes associated to TEV-cis-eQTLs and genes associated to the genomic regions mostly enriched in TEV-cis-eQTLs highlighting, at multiple levels, the impact of TEVs on the host genome. Finally, we also identified polymorphic TEs putatively embedded in transcriptional units, proposing a novel mechanism in which TEVs may mediate individual-specific traits.

Conclusion

We contributed to unveiling the effect of polymorphic TEs on transcription in lymphoblastoid cell lines.

Developmental neurogenetics and multimodal neuroimaging of sex differences in autism

Examining sex differences in the brain has been historically contentious but is nonetheless important for advancing mental health for both girls and boys. Unfortunately, females in biomedical research remain underrepresented in most mental health conditions including autism spectrum disorders (ASD), even though equal inclusion of females would improve treatment for girls and yield benefits to boys. This review examines sex differences in the relationship between neuroanatomy and neurogenetics of ASD. Recent findings reveal that girls diagnosed with ASD exhibit more intellectual and behavioral problems compared to their male counterparts, suggesting that girls may be less likely diagnosed in the absence of such problems or that they require a higher mutational load to meet the diagnostic criteria. Thus far, the female biased effect of chromosome 4, 5p15.33, 8p, 9p24.1, 11p12-13, 15q, and Xp22.3 and the male biased effect of 1p31.3, 5q12.3, 7q, 9q33.3, 11q13.4, 13q33.3, 16p11.2, 17q11-21, Xp22.33/Yp11.31, DRD1, NLGN3, MAOA, and SHANK1 deletion have been discovered in ASD. The SNPs of genes such as RYR2, UPP2, and the androgen receptor gene have been shown to have sex-biasing factors in both girls and boys diagnosed with ASD. These sex-related genetic factors may drive sex differences in the neuroanatomy of these girls and boys, including abnormal enlargement in temporal gray and white matter volumes, and atypical reduction in cerebellar gray matter volumes and corpus callosum fibers projecting to the anterior frontal cortex in ASD girls relative to boys. Such factors may also be responsible for the attenuation of brain sexual differentiation in adult men and women with ASD; however, much remains to be uncovered or replicated. Future research should leverage further the association between neuroanatomy and genetics in girls for an integrated and interdisciplinary understanding of ASD.

Early fetal presentation of Koolen-de Vries: Case report with literature review

Koolen-de Vries syndrome (MIM#610443) is a rare microdeletion syndrome involving the 17q21.31 region, which was first described by Koolen in 2006. Clinical and behavioral characteristics have been extensively reported from more than 100 postnatal cases including infants, children and young adults. The syndrome is highly clinically heterogeneous, but the main features associate characteristic cranio-facial dysmorphism, heart defects, limb, skeletal, genito-urinary anomalies, along with intellectual disability with early childhood epilepsy and behavioral disturbances. Central nervous system malformations usually consist in hydrocephalus and thin corpus callosum. We report herein an early fetal case with an apparently isolated abnormal corpus callosum diagnosed by ultrasonography, for which a medical termination of the pregnancy was achieved at 22 weeks of gestation. Postmortem examination displayed facial dysmorphism consisting of hypertelorism, short philtrum and flat and broad nose, cleft palate and left duplex ureter. Neuropathological examination revealed a mega corpus callosum that has never been reported so far in this syndrome. Array-CGH performed on thymic DNA tissue revealed a 17q21.31 microdeletion, which allowed for the confirmation of early occurring Koolen-de Vries syndrome.

Molecular Characterization of Koolen De Vries Syndrome in Two Girls with Idiopathic Intellectual Disability from Central Brazil

Koolen de Vries syndrome (KDVS; MIM 610443) is a genomic disorder caused by a recurrent microdeletion derived from nonallelic homologous recombination mediated by flanking segmental duplications. Clinical manifestations of this syndrome are characterized by intellectual disability, hypotonia, a friendly behavior, distinctive facial features, and epilepsy. Herein, we report a case of 2 girls who revealed global developmental delay, mild facial dysmorphisms, friendly behavior, and epileptic seizure with a de novo 17q21.31 microdeletion detected by chromosomal microarray analysis (CMA). Conventional cytogenetics analysis by GTG-banding showed a female karyotype 46,XX for both girls. CMA revealed a microdeletion spanning approximately 500 kb in 17q21.31 in both girls, encompassing the following genes: CRHR1, MGC57346, CRHR1-IT1, MAPT-AS1, SPPL2C, MAPT, MAPT-IT1, STH, and KANSL1. Haploinsufficiency of one or more of these genes within the deleted region is the most probable cause of the probands' phenotype and is responsible for the phenotype seen in KDVS. CMA is a powerful diagnostic tool and an effective method to identify the de novo 17q21.31 microdeletion associated with KDVS in our probands.