Progressive Myoclonus Epilepsy Caused by a Homozygous Splicing Variant of SLC7A6OS.

Exome sequencing was performed in 2 unrelated families with progressive myoclonus epilepsy. Affected individuals from both families shared a rare, homozygous c.191A > G variant affecting a splice site in SLC7A6OS. Analysis of cDNA from lymphoblastoid cells demonstrated partial splice site abolition and the creation of an abnormal isoform. Quantitative reverse transcriptase polymerase chain reaction and Western blot showed a marked reduction of protein expression. Haplotype analysis identified a ~0.85cM shared genomic region on chromosome 16q encompassing the c.191A > G variant, consistent with a distant ancestor common to both families. Our results suggest that biallelic loss-of-function variants in SLC7A6OS are a novel genetic cause of progressive myoclonus epilepsy. ANN NEUROL 2021;89:402-407.

Bi-allelic GAD1 variants cause a neonatal onset syndromic developmental and epileptic encephalopathy.

Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing the phenotype of the knockout Gad1-/- mouse model. Four patients died before 4 years of age. GAD1 encodes the glutamate decarboxylase enzyme GAD67, a critical actor of the γ-aminobutyric acid (GABA) metabolism as it catalyses the decarboxylation of glutamic acid to form GABA. Our findings evoke a novel syndrome related to GAD67 deficiency, characterized by the unique association of developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele.

A Case of Trisomy 13 Mosaicism Presenting with a Severe Aortic Root Dilatation and Marfanoid Habitus due to an Unpredictable Cytogenetic Mechanism.

In this report, we present a new case of mosaic trisomy 13 with prolonged survival, firstly detected by array-CGH analysis which was carried out because of moderate intellectual disability with postaxial hexadactyly, dermatologic features, ventricular septal defect, bicuspid aortic valve, and aortic dystrophy in a 19-year-old male patient. In a subset of 15% of the cells, the patient carried a derivative chromosome 10 generated by a nonreciprocal (10;13) translocation inherited from his healthy mother who carried the translocation in a balanced and homogeneous state. FISH analyses showed interstitial telomeric sequences at the breakpoints. To our knowledge, this is the second report of a patient with trisomy 13 mosaicism displaying a severe aortic root dilatation. We also discuss the mechanisms which could explain the mosaic state, the most likely one being related to the instability of the interstitial telomere.

Growth charts in Kabuki syndrome 1.

Kabuki syndrome (KS, KS1: OMIM 147920 and KS2: OMIM 300867) is caused by pathogenic variations in KMT2D or KDM6A. KS is characterized by multiple congenital anomalies and neurodevelopmental disorders. Growth restriction is frequently reported. Here we aimed to create specific growth charts for individuals with KS1, identify parameters used for size prognosis and investigate the impact of growth hormone therapy on adult height. Growth parameters and parental size were obtained for 95 KS1 individuals (41 females). Growth charts for height, weight, body mass index (BMI) and occipitofrontal circumference were generated in standard deviation values for the first time in KS1. Statural growth of KS1 individuals was compared to parental target size. According to the charts, height, weight, BMI, and occipitofrontal circumference were lower for KS1 individuals than the normative French population. For males and females, the mean growth of KS1 individuals was -2 and -1.8 SD of their parental target size, respectively. Growth hormone therapy did not increase size beyond the predicted size. This study, from the largest cohort available, proposes growth charts for widespread use in the management of KS1, especially for size prognosis and screening of other diseases responsible for growth impairment beyond a calculated specific target size.

A novel lethal recognizable polymicrogyric syndrome caused by ATP1A2 homozygous truncating variants.

Polymicrogyria is a heterogeneous malformation of cortical development microscopically defined by an excessive folding of the cortical mantle resulting in small gyri with a fused surface. Polymicrogyria is responsible for a wide range of neurological symptoms (e.g. epilepsy, intellectual disability, motor dysfunction). Most cases have a supposed environmental clastic vascular or infectious origin but progress in genomics has revealed new monogenic entities. We report four cases from two independent families sharing a common recognizable lethal syndromic polymicrogyria of autosomal recessive inheritance. Beyond diffuse polymicrogyria detected prenatally, pathological examination revealed a common pattern associating meningeal arterial calcifications, necrotic and calcified areas in basal ganglia, dentato-olivary dysplasia and severe hypoplasia/agenesis of the pyramidal tracts. In all affected cases, exome sequencing showed a pathogenic homozygous nonsense ATP1A2 variant. This resulted in absence of immunodetectable ATP1A2 protein in two brains analysed. ATP1A2 encodes the alpha-2 isoform of the Na+/K+-ATPase, which is highly expressed in brain tissues and has previously been related to familial hemiplegic migraine (MIM#602481) and alternating hemiplegia of childhood (MIM#104290). Through the description of this genetic entity, we emphasize the possibility of dual mode of transmission for disease-causing genes and provide the key neuropathological features that should prompt geneticists to test for mutations in the ATP1A2 gene.

Centralization errors in comparative genomic hybridization array analysis of pituitary tumor samples.

Reliable interpretation of comparative genomic hybridization array (aCGH) results requires centralization and normalization of the data. We evaluated the reliability of aCGH centralization by comparing aCGH results (with classical centralization-normalization steps) to fluorescence in situ hybridization (FISH) results. In addition, we propose a method to correct centralization bias. Sixty-six pituitary tumors were analyzed (Agilent aCGH + SNP 4 × 180K microarray). For each tumor, the FISH-based log2 (ratios) of a subset of chromosomes were compared with the corresponding aCGH raw log2 (ratios). With our new normalization-centralization process, this difference was added to all log2 (ratios), before performing loess regression on non-altered probes only. Finally, the mean log2 (ratio) and the percentage of normal probes were compared between CGHnormaliter and our new FISH-based method. For 11 tumors, FISH results and raw CGH log2 (ratios) differed significantly. In addition, nine tumors showed discrepancies between results generated by CGHnormaliter and our new-method. Such discrepancies seemed to occur with tumours with many abnormalities (0%-40% normal probes), rather than in those tumours with fewer abnormalities (31%-100% normal probes). Five tumors had too few normal probes to allow normalization. In these tumors, which can exhibit many changes in DNA copy number, we found that centralization bias was frequent and uncorrected by current normalization methods. Therefore, an external control for centralization, such as FISH analysis, is required to insure reliable interpretation of aCGH data.

Prenatal Diagnosis of Trisomy 2p due to Terminal 2p Duplication including Interstitial Telomeric Sequences.

We report on a prenatally diagnosed unusual case of inverted terminal duplication of the short arm of chromosome 2, leading to interstitial telomeric sequences (ITSs) and partial trisomy 2p. To our knowledge, there are only 4 further cases of pure partial trisomy 2p reported prenatally. Here, the mother was referred at 22 weeks of gestation for isolated fetal congenital heart malformation at ultrasound. The karyotype of amniotic fluid cells displayed a large duplication of the short arm of chromosome 2 that was further investigated by array-CGH, which detected a 1-copy gain of 43.75 Mb in chromosome 2 at 2p21p25.3. FISH confirmed the presence of an inverted duplication in the short arm of chromosome 2 involving the region 2p21pter and revealed the presence of ITSs at the breakpoint in chromosome 2p21. This report contributes to the prenatal description of the syndrome. We also discuss the possible mechanisms leading to this duplication and the formation of ITSs which are rarely described in constitutional rearrangements.

The workflow from post-mortem human brain sampling to cell microdissection: a Brain Net Europe study.

Brain banks manage and store fully clinically and pathologically characterised brains. The diversity of techniques used in research projects increases. These biological resource centres are made to adapt brain tissue processing. Furthermore, the development of more sensitive techniques to analyse nucleic acids and proteins offers new fields of exploration when combined with laser capture microdissection in order to decipher the physiopathology of diseases at the cell level. In this study, our goal was to evaluate procedures and set a workflow compatible with the constraints of brain banks, from brain sampling to laser capture microdissection and pre-analytical quality assessment. We compared various methods of freezing brain tissue, focused on morphological quality preservation of brain microscopical structures and on the quality of nucleic acid or protein yields. Staining protocols combined with strategies to lower neurones autofluorescence were adapted for the same purpose. Finally, we found that laser capture microdissection is possible in the setting of brain banks. However, the entire process has to be envisioned from the autopsy to the analysis. The impact on protein or nucleic acid quality is a limitation that restricts the amount of samples available for this purpose.

Clinical and molecular spectrum of renal malformations in Kabuki syndrome.

OBJECTIVE: To determine the frequency and types of renal malformations, and to evaluate renal function in a cohort of patients with Kabuki syndrome (KS). STUDY DESIGN: Renal ultrasound scans and plasma creatinine measurements were collected from a French cohort of 94 patients with genotyped KS. Renal function was evaluated based on the estimated glomerular filtration rate. A genotype-phenotype study was conducted for renal and urinary tract malformations. RESULTS: Renal malformations were present in 22% of cases, and urinary tract anomalies were present in 15%. Renal malformations were observed in 28% of the MLL2 mutation-positive group and in 0% of the MLL2 mutation-negative group (P = .015). No correlation was found between the presence or absence of renal or urinary tract malformations and the location or type of MLL2 mutation. Renal function was normal except for 1 patient with a MLL2 mutation diagnosed in the first days of life and severe renal disease due to unilateral renal agenesia and controlateral severe hypoplasia that progressed to the terminal stage at age 2 years. CONCLUSION: Our study emphasizes the need for ultrasound and renal function screening in children diagnosed with KS.

Variability in CD39 and CD73 protein levels in uveal melanoma patients.

Extracellular adenosine is produced from ATP by CD39 and CD73, and can modulate tumor development by acting on cancer cells or immune cells. Adenosine metabolism has been poorly studied in uveal melanoma. We studied the protein levels of CD39 and CD73 in a small, well described cohort of patients with uveal melanoma. Our results show a high variability in the levels of the two proteins, both in positivity and in intensity. Our results suggest that similar studies on larger cohorts could determine the clinical value and the druggability of these enzymes in the given clinical setting.Supplemental data for this article is available online at http://dx.doi.org/10.1080/15257770.2022.2032738.

Case report: 7p22.3 deletion and 8q24.3 duplication in a patient with epilepsy and psychomotor delay-Does both possibly act to modulate a candidate gene region for the patient's phenotype?

Background: Psychomotor delay, epilepsy and dysmorphic features are clinical signs which are described in multiple syndromes due to chromosomal imbalances or mutations involving key genes implicated in the stages of Early Embryonic Development. In this context, we report a 10 years old Tunisian patient with these three signs. Our objective is to determine the cause of developmental, behavioral and facial abnormalities in this patient. Methods: We used banding cytogenetics (karyotype) and Array Comparative Genomic Hybridization (Array CGH) to this purpose. Results: The karyotype was in favor of a derivative of chromosome 7 in the patient and Array CGH analysis revealed a loss of genetic material in 7p22.3-p22.1 (4,56 Mb) with a gain at 8q24.23-q24 (9.20 Mb) resulting from maternal 7/8 reciprocal translocation. An in silico analysis of the unbalanced region was carried out and showed that the 7p22.3-p22.1 deletion contains eight genes. Among them, BRAT1 gene, previously described in several neurodevelopmental diseases, may be a candidate gene which absence could be correlated to the patient's phenotype. However, the 8q24.23-q24 duplication could be involved in the phenotype of this patient. Conclusion: In this study, we report for the first time a 7p deletion/8q duplication in a patient with psychomoteur delay, epilepsy and facial dysmorphism. Our study showed that Array CGH still useful for delivering a conclusive genetic diagnosis for patients having neurodevelopmental abnormalities in the era of next-generation sequencing.

Multisystem disorders, severe developmental delay and seizures in two affected siblings, expanding the phenotype of PIGC deficiency.

PIGC (OMIM 601730) encodes the PIGC protein, which is part of an enzyme complex involved in the biosynthesis of the glycosylphosphatidylinositol protein anchor. The other proteins in the complex include PIGA, PIGH, PIGQ, PIGY, PIGP and DPM2. Homozygous and compound heterozygous mutations in PIGC have recently been described to cause severe global developmental delay, intellectual disability, and seizures in two unrelated families, without indication of another system involvement or dysmorphism. Here we describe two siblings, born to second cousin parents, displaying severe psychomotor delay, seizures, organomegaly, cardiopulmonary anomalies, and similar facial dysmorphism. Exome sequencing in the boy revealed a homozygous variant in PIGC gene, c.12_13insTTGTGACTAACA leading to a premature stop codon p.(Gln4_Pro5insLeu*). His affected sister was also found to be homozygous, and their parents were found to be heterozygous. This is the first detailed clinical description of two related patients suggesting that PIGC deficiency can cause a severe recognisable phenotype including multisystem disorders, in association to previously reported severe developmental delay and seizures.

SST5 expression and USP8 mutation in functioning and silent corticotroph pituitary tumors.

OBJECTIVE: Somatostatin receptor type 5 (SST5) is inconsistently expressed by corticotroph tumors, with higher expression found in corticotropinomas having ubiquitin-specific protease 8 (USP8) mutations. Aims were to study the correlation between characteristics of corticotropinomas and SST5 expression/USP8 mutation status and to describe the response to pasireotide in 5 patients. DESIGN: Retrospective cohort study. METHODS: Clinico-biochemical, radiological and pathological data of 62 patients, operated for a functioning or silent corticotropinoma between 2013 and 2017, were collected. SST5 expression was measured by immunohistochemistry (clone UMB-4, Abcam, IRS>1 being considered positive) and Sanger sequencing was performed on 50 tumors to screen for USP8 mutations. RESULTS: SST5 expression was positive in 26/62 pituitary tumors. A moderate or strong IRS was found in 15/58 corticotropinomas and in 13/35 functioning corticotropinomas. Among functioning tumors, those expressing SST5 were more frequent in women (22/24 vs 9/15, P=0.04) and had a lower grade (P=0.04) compared to others. USP8 mutations were identified in 13/50 pituitary tumors and were more frequent in functioning compared to silent tumors (11/30 vs 2/20, P=0.05). SST5 expression was more frequent in USP8mut vs USP8wt tumors (10/11 vs 7/19, P=0.007). Among treated patients, normal urinary free cortisol levels were obtained in 3 patients (IRS 0, 2, 6) while a 4-fold decrease was observed in one patient (IRS 4). CONCLUSION: SST5 expression appears to be associated with functioning, USP8mut and lower grade corticotropinomas. A correlation between SST5 expression or USP8mut and response to pasireotide remains to be confirmed.

Chromosomal instability in the prediction of pituitary neuroendocrine tumors prognosis.

The purpose of this study was to analyze the impact of copy number variations (CNV) on sporadic pituitary neuroendocrine tumors (PitNETs) prognosis, to identify specific prognosis markers according to the known clinico-pathological classification. CGH array analysis was performed on 195 fresh-frozen PitNETs (56 gonadotroph, 11 immunonegative, 56 somatotroph, 39 lactotroph and 33 corticotroph), with 5 years post-surgery follow-up (124 recurrences), classified according to the five-tiered grading classification (invasion, Ki-67, mitotic index and p53 positivity). Effect of alterations on recurrence was studied using logistic regression models. Transcriptomic analysis of 32 lactotroph tumors was performed. The quantity of CNV was dependent on tumor type: higher in lactotroph (median(min-max) = 38% (0-97) of probes) compared to corticotroph (11% (0-77)), somatotroph (5% (0-99)), gonadotroph (0% (0-10)) and immunonegative tumors (0% (0-17). It was not predictive of recurrence in the whole cohort. In lactotroph tumors, genome instability, especially quantity of gains, significantly predicted recurrence independently of invasion and proliferation (p-value = 0.02, OR = 1.2). However, no specific CNV was found as a prognostic marker. Transcriptomic analysis of the genes included in the CNV and associated with prognosis didn't show significantly overrepresented pathway. In somatotroph and corticotroph tumors, USP8 and GNAS mutations were not associated with genome disruption or recurrence respectively. To conclude, CGH array analysis showed genome instability was dependent on PitNET type. Lactotroph tumors were highly altered and the quantity of altered genome was associated with poorer prognosis though the mechanism is unclear, whereas gonadotroph and immunonegative tumors showed the same 'quiet' profile, leaving the mechanism underlying tumorigenesis open to question.

Prostaglandin E2 metabolism in rat brain: Role of the blood-brain interfaces.

BACKGROUND: Prostaglandin E2 (PGE2) is involved in the regulation of synaptic activity and plasticity, and in brain maturation. It is also an important mediator of the central response to inflammatory challenges. The aim of this study was to evaluate the ability of the tissues forming the blood-brain interfaces to act as signal termination sites for PGE2 by metabolic inactivation. METHODS: The specific activity of 15-hydroxyprostaglandin dehydrogenase was measured in homogenates of microvessels, choroid plexuses and cerebral cortex isolated from postnatal and adult rat brain, and compared to the activity measured in peripheral organs which are established signal termination sites for prostaglandins. PGE2 metabolites produced ex vivo by choroid plexuses were identified and quantified by HPLC coupled to radiochemical detection. RESULTS: The data confirmed the absence of metabolic activity in brain parenchyma, and showed that no detectable activity was associated with brain microvessels forming the blood-brain barrier. By contrast, 15-hydroxyprostaglandin dehydrogenase activity was measured in both fourth and lateral ventricle choroid plexuses from 2-day-old rats, albeit at a lower level than in lung or kidney. The activity was barely detectable in adult choroidal tissue. Metabolic profiles indicated that isolated choroid plexus has the ability to metabolize PGE2, mainly into 13,14-dihydro-15-keto-PGE2. In short-term incubations, this metabolite distributed in the tissue rather than in the external medium, suggesting its release in the choroidal stroma. CONCLUSION: The rat choroidal tissue has a significant ability to metabolize PGE2 during early postnatal life. This metabolic activity may participate in signal termination of centrally released PGE2 in the brain, or function as an enzymatic barrier acting to maintain PGE2 homeostasis in CSF during the critical early postnatal period of brain development.

Functional variants of POC5 identified in patients with idiopathic scoliosis.

Idiopathic scoliosis (IS) is a spine deformity that affects approximately 3% of the population. The underlying causes of IS are not well understood, although there is clear evidence that there is a genetic component to the disease. Genetic mapping studies suggest high genetic heterogeneity, but no IS disease-causing gene has yet been identified. Here, genetic linkage analyses combined with exome sequencing identified a rare missense variant (p.A446T) in the centriolar protein gene POC5 that cosegregated with the disease in a large family with multiple members affected with IS. Subsequently, the p.A446T variant was found in an additional set of families with IS and in an additional 3 cases of IS. Moreover, POC5 variant p.A455P was present and linked to IS in one family and another rare POC5 variant (p.A429V) was identified in an additional 5 cases of IS. In a zebrafish model, expression of any of the 3 human IS-associated POC5 variant mRNAs resulted in spine deformity, without affecting other skeletal structures. Together, these findings indicate that mutations in the POC5 gene contribute to the occurrence of IS.

Neuropathological features in a female fetus with OPHN1 deletion and cerebellar hypoplasia.

We report the case of a 33-year-old pregnant woman. The third-trimester ultrasound scan during pregnancy revealed fetal bilateral ventricular dilatation, macrosomia and a transverse diameter of the cerebellum at the 30th centile. A brain MRI scan at 31 weeks of gestation led to a diagnosis of hypoplasia of the cerebellar vermis without hemisphere abnormalities and a non compressive expansion of the cisterna magna. The fetal karyotype was 46,XX. The pregnancy was terminated and array-CGH analysis of the fetus identified a 238 kb de novo deletion on chromosome Xp12, encompassing part of OPHN1 gene. Further studies revealed a completely skewed pattern of X inactivation. OPHN1 is involved in X-linked mental retardation (XLMR) with cerebellar hypoplasia and encodes a Rho-GTPase-activating protein called oligophrenin-1, which is produced throughout the developing mouse brain and in the hippocampus and Purkinje cells of the cerebellum in adult mice. Neuropathological examination of the female fetus revealed cerebellar hypoplasia and the heterotopia of Purkinje cells at multiple sites in the white matter of the cerebellum. This condition mostly affects male fetuses in humans. We report here the first case of a de novo partial deletion of OPHN1, with radiological and neuropathological examination, in a female fetus.

Finger creases lend a hand in Kabuki syndrome.

Kabuki syndrome (KS) is a rare syndrome associating malformations with intellectual deficiency and numerous visceral, orthopedic, endocrinological, immune and autoimmune complications. The early establishment of a diagnostic of KS leads to better care of the patients and therefore prevents complications such as perception deafness, severe complications of auto-immune diseases or obesity. However, the diagnosis of KS remains difficult because based on the appreciation of facial features combined with other highly variable features. We describe a novel sign, namely the attenuation and/or congenital absence of the IPD crease of the third and fourth fingers associated with limitation of flexion of the corresponding joints, which seems to be specific of KS and could help the clinician to diagnose KS.