The Immune Signaling Adaptor LAT Contributes to the Neuroanatomical Phenotype of 16p11.2 BP2-BP3 CNVs.

Copy-number changes in 16p11.2 contribute significantly to neuropsychiatric traits. Besides the 600 kb BP4-BP5 CNV found in 0.5%-1% of individuals with autism spectrum disorders and schizophrenia and whose rearrangement causes reciprocal defects in head size and body weight, a second distal 220 kb BP2-BP3 CNV is likewise a potent driver of neuropsychiatric, anatomical, and metabolic pathologies. These two CNVs are engaged in complex reciprocal chromatin looping, intimating a functional relationship between genes in these regions that might be relevant to pathomechanism. We assessed the drivers of the distal 16p11.2 duplication by overexpressing each of the nine encompassed genes in zebrafish. Only overexpression of LAT induced a reduction of brain proliferating cells and concomitant microcephaly. Consistently, suppression of the zebrafish ortholog induced an increase of proliferation and macrocephaly. These phenotypes were not unique to zebrafish; Lat knockout mice show brain volumetric changes. Consistent with the hypothesis that LAT dosage is relevant to the CNV pathology, we observed similar effects upon overexpression of CD247 and ZAP70, encoding members of the LAT signalosome. We also evaluated whether LAT was interacting with KCTD13, MVP, and MAPK3, major driver and modifiers of the proximal 16p11.2 600 kb BP4-BP5 syndromes, respectively. Co-injected embryos exhibited an increased microcephaly, suggesting the presence of genetic interaction. Correspondingly, carriers of 1.7 Mb BP1-BP5 rearrangements that encompass both the BP2-BP3 and BP4-BP5 loci showed more severe phenotypes. Taken together, our results suggest that LAT, besides its well-recognized function in T cell development, is a major contributor of the 16p11.2 220 kb BP2-BP3 CNV-associated neurodevelopmental phenotypes.

Estimating the effect size of the 15Q11.2 BP1-BP2 deletion and its contribution to neurodevelopmental symptoms: recommendations for practice.

BACKGROUND: The 15q11.2 deletion is frequently identified in the neurodevelopmental clinic. Case-control studies have associated the 15q11.2 deletion with neurodevelopmental disorders, and clinical case series have attempted to delineate a microdeletion syndrome with considerable phenotypic variability. The literature on this deletion is extensive and confusing, which is a challenge for genetic counselling. The aim of this study was to estimate the effect size of the 15q11.2 deletion and quantify its contribution to neurodevelopmental disorders. METHODS: We performed meta-analyses on new and previously published case-control studies and used statistical models trained in unselected populations with cognitive assessments. We used new (n=241) and previously published (n=150) data from a clinically referred group of deletion carriers. 15q11.2 duplications (new n=179 and previously published n=35) were used as a neutral control variant. RESULTS: The deletion decreases IQ by 4.3 points. The estimated ORs and respective frequencies in deletion carriers for intellectual disabilities, schizophrenia and epilepsy are 1.7 (3.4%), 1.5 (2%) and 3.1 (2.1%), respectively. There is no increased risk for heart malformations and autism. In the clinically referred group, the frequency and nature of symptoms in deletions are not different from those observed in carriers of the 15q11.2 duplication suggesting that most of the reported symptoms are due to ascertainment bias. CONCLUSIONS: We recommend that the deletion should be classified as 'pathogenic of mild effect size'. Since it explains only a small proportion of the phenotypic variance in carriers, it is not worth discussing in the developmental clinic or in a prenatal setting.

Intravenous immunoglobulin treatment in a patient with adrenomyeloneuropathy.

BACKGROUND: Adrenomyeloneuropathy (AMN) is one of several phenotypes of the adrenoleukodystrophy spectrum caused by mutations in the ABCD1 gene on the X chromosome. An inflammatory component is part of the disease complex ranging from severe childhood CNS demyelination to spinal cord and peripheral nerve degeneration. CASE PRESENTATION: We present a patient with clinical progressive AMN and severe lower limb pain. Longitudinal brain magnetic resonance spectroscopy showed a constant slightly elevated myoinositol/total creatine ratio during the five year treatment period, probably reflecting demyelination, microglial activation and gliosis, indicating an inflammatory response. The pain was refractory to conventional therapy but intravenous immunoglobulin (IVIG) treatment was highly efficient. CONCLUSION: IVIG may be considered as a last resort for treatment of refractory pain in AMN patients with indications of an inflammatory component.

Phenotypic manifestations in FLNA-related periventricular nodular heterotopia: a case report and review of the literature.

Periventricular nodular heterotopia (PVNH) is an X-linked disease caused by loss-of-function variants in the filamin A (FLNA) gene. FLNA-PVNH is a heterogeneous disorder, and the phenotype is associated with neurological and non-neurological features including cardiovascular, gastrointestinal, pulmonary, haematological, cutaneous and skeletal manifestations. No clear definition of the FLNA-PVNH phenotype has been established, but the patients are predominantly females with seizures, cardiovascular manifestations, and normal intelligence or mild intellectual disability. Herein, we describe a PVNH patient diagnosed with a novel heterozygous missense variant in FLNA after an atypical presentation of deep vein thrombosis and thrombocytopenia. Clinical evaluation found hypermobility, cardiovascular and skin manifestations. Moreover, we conducted a literature review of 186 FLNA-PVNH patients to describe the phenotypic spectrum. In conclusion, our patient highlights the importance of thorough clinical evaluation to identify manifestations in this very heterogeneous disorder. The phenotypic review may guide clinicians in the assessment and follow-up of FLNA-PVNH patients.

A three-generation family with idiopathic facial palsy suggesting an autosomal dominant inheritance with high penetrance.

Idiopathic facial palsy (IFP), also known as Bell's palsy, is a common neurologic disorder, but recurrent and familial forms are rare. This case series presents a three-generation family with idiopathic facial palsy. The mode of inheritance of IFP has previously been suggested as autosomal dominant with low or variable penetrance, but the present family indicates an autosomal dominant trait with high or complete penetrance. Chromosome microarray studies did not reveal a pathogenic copy number variation, which could enable identification of a candidate gene.

[Carriers of fragile X syndrome can present with a broad spectrum of clinical disorders]. / Anlægsbærere for fragilt X-syndrom kan udvise et bredt spektrum af kliniske manifestationer

Fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI) are three clinically distinct disorders caused by expansions of a CGG repeat sequence in the non-coding part of the FMR1. FXTAS and FXPOI are seen in carriers of smaller repeat expansions (55-200). Carriers were for many years thought to be clinically unaffected, but along with the discovery of FXPOI and FXTAS a growing number of additional clinical manifestations have been identified. We wish to make Danish physicians more aware of these conditions which we review in this paper.

[From intellectual disability to new treatment modalities of fragile X syndrome]. / Fra mental retardering til målrettet behandling ved fragilt X-syndrom.

In 1943 a large family with X-linked mental retardation was described by Martin & Bell. This family had what we know today as fragile X syndrome, the most common inherited form of intellectual disability. Current knowledge about the specific gene, the encoded protein and the pathophysiological mechanisms involved has made it possible to develop pharmacological treatment trials. Fragile X syndrome therefore is on its way as model disorder for targeted treatments in genetic medicine, and this article reviews clinical and therapeutic aspects of the syndrome.

De novo microdeletions of chromosome 6q14.1-q14.3 and 6q12.1-q14.1 in two patients with intellectual disability - further delineation of the 6q14 microdeletion syndrome and review of the literature.

Interstitial 6q deletions can cause a variable phenotype depending on the size and location of the deletion. 6q14 deletions have been associated with intellectual disability and a distinct pattern of minor anomalies, including upslanted palpebral fissures with epicanthal folds, a short nose with broad nasal tip, anteverted nares, long philtrum, and thin upper lip. In this study we describe two patients with overlapping 6q14 deletions presenting with developmental delay and characteristic dysmorphism. Molecular karyotyping using array CGH analysis revealed a de novo 8.9 Mb deletion at 6q14.1-q14.3 and a de novo 11.3 Mb deletion at 6q12.1-6q14.1, respectively. We provide a review of the clinical features of twelve other patients with 6q14 deletions detected by array CGH analysis. By assessing all reported data we could not identify a single common region of deletion. Possible candidate genes in 6q14 for intellectual disability might be FILIP1, MYO6, HTR1B, and SNX14.