Biallelic null variants in PNPLA8 cause microcephaly by reducing the number of basal radial glia.

Patatin-like phospholipase domain-containing lipase 8 (PNPLA8), one of the calcium-independent phospholipase A2 enzymes, is involved in various physiological processes through the maintenance of membrane phospholipids. Biallelic variants in PNPLA8 have been associated with a range of paediatric neurodegenerative disorders. However, the phenotypic spectrum, genotype-phenotype correlations and the underlying mechanisms are poorly understood. Here, we newly identified 14 individuals from 12 unrelated families with biallelic ultra-rare variants in PNPLA8 presenting with a wide phenotypic spectrum of clinical features. Analysis of the clinical features of current and previously reported individuals (25 affected individuals across 20 families) showed that PNPLA8-related neurological diseases manifest as a continuum ranging from variable developmental and/or degenerative epileptic-dyskinetic encephalopathy to childhood-onset neurodegeneration. We found that complete loss of PNPLA8 was associated with the more profound end of the spectrum, with congenital microcephaly. Using cerebral organoids generated from human induced pluripotent stem cells, we found that loss of PNPLA8 led to developmental defects by reducing the number of basal radial glial cells and upper-layer neurons. Spatial transcriptomics revealed that loss of PNPLA8 altered the fate specification of apical radial glial cells, as reflected by the enrichment of gene sets related to the cell cycle, basal radial glial cells and neural differentiation. Neural progenitor cells lacking PNPLA8 showed a reduced amount of lysophosphatidic acid, lysophosphatidylethanolamine and phosphatidic acid. The reduced number of basal radial glial cells in patient-derived cerebral organoids was rescued, in part, by the addition of lysophosphatidic acid. Our data suggest that PNPLA8 is crucial to meet phospholipid synthetic needs and to produce abundant basal radial glial cells in human brain development.

Novel KIF26A variants associated with pediatric intestinal pseudo-obstruction (PIPO) and brain developmental defects.

Pediatric intestinal pseudo-obstruction (PIPO) is a rare congenital disorder of the enteric nervous system with distal colon aganglionosis potentially leading to intestinal obstruction. Recently, biallelic variants in KIF26A, encoding a crucial motor protein for the migration and differentiation of enteric neural crest cells, have been associated with a neurodevelopmental condition featuring cortical defects and PIPO-like features, though in absence of aganglionosis. So far, only 10 patients have been reported. In this study, we investigated three subjects with congenital hydrocephalus, neurodevelopmental impairment, and intestinal obstruction megacolon syndrome. Brain MRI revealed malformations within cortical dysplasia spectrum, including polymicrogyria and heterotopia. Pathology study of the intestine revealed aganglionosis and elevated acetylcholinesterase activity in parasympathetic nerve fibers. Through trio-exome sequencing (ES), we detected four novel biallelic KIF26A variants, including two missense changes (#1) and two distinct homozygous truncating variants in (#2 and #3). All variants are rare and predicted to be deleterious according to in silico tools. To characterize the impact of the missense variants, we performed 3D protein modeling using Alphafold3 and YASARA. Mutants exhibited increased energy scores compared to wild-type protein, supporting a significant structural destabilization of the protein. Our study expands the genotype and phenotype spectrum of the emerging KIF26A-related disorder.

O'Donnell-Luria-Rodan syndrome: description of a second multinational cohort and refinement of the phenotypic spectrum.

BACKGROUND: O'Donnell-Luria-Rodan syndrome (ODLURO) is an autosomal-dominant neurodevelopmental disorder caused by pathogenic, mostly truncating variants in KMT2E. It was first described by O'Donnell-Luria et al in 2019 in a cohort of 38 patients. Clinical features encompass macrocephaly, mild intellectual disability (ID), autism spectrum disorder (ASD) susceptibility and seizure susceptibility. METHODS: Affected individuals were ascertained at paediatric and genetic centres in various countries by diagnostic chromosome microarray or exome/genome sequencing. Patients were collected into a case cohort and were systematically phenotyped where possible. RESULTS: We report 18 additional patients from 17 families with genetically confirmed ODLURO. We identified 15 different heterozygous likely pathogenic or pathogenic sequence variants (14 novel) and two partial microdeletions of KMT2E. We confirm and refine the phenotypic spectrum of the KMT2E-related neurodevelopmental disorder, especially concerning cognitive development, with rather mild ID and macrocephaly with subtle facial features in most patients. We observe a high prevalence of ASD in our cohort (41%), while seizures are present in only two patients. We extend the phenotypic spectrum by sleep disturbances. CONCLUSION: Our study, bringing the total of known patients with ODLURO to more than 60 within 2 years of the first publication, suggests an unexpectedly high relative frequency of this syndrome worldwide. It seems likely that ODLURO, although just recently described, is among the more common single-gene aetiologies of neurodevelopmental delay and ASD. We present the second systematic case series of patients with ODLURO, further refining the mutational and phenotypic spectrum of this not-so-rare syndrome.

Corneal Infantile Myofibromatosis Caused by Novel Activating Imatinib-Responsive Variants in PDGFRB.

Purpose: To investigate the genetic cause, clinical characteristics, and potential therapeutic targets of infantile corneal myofibromatosis. Design: Case series with genetic and functional in vitro analyses. Participants: Four individuals from 2 unrelated families with clinical signs of corneal myofibromatosis were investigated. Methods: Exome-based panel sequencing for platelet-derived growth factor receptor beta gene (PDGFRB) and notch homolog protein 3 gene (NOTCH3) was performed in the respective index patients. One clinically affected member of each family was tested for the pathogenic variant detected in the respective index by Sanger sequencing. Immunohistochemical staining on excised corneal tissue was conducted. Functional analysis of the individual PDGFRB variants was performed in vitro by luciferase reporter assays on transfected porcine aortic endothelial cells using tyrosine kinase inhibitors. Protein expression analysis of mutated PDGFRB was analyzed by Western blot. Main Outcome Measures: Sequencing data, immunohistochemical stainings, functional analysis of PDGFRB variants, and protein expression analysis. Results: We identified 2 novel, heterozygous gain-of-function variants in PDGFRB in 4 individuals from 2 unrelated families with corneal myofibromatosis. Immunohistochemistry demonstrated positivity for alpha-smooth muscle actin and ß-catenin, a low proliferation rate in Ki-67 (< 5%), marginal positivity for Desmin, and negative staining for Caldesmon and CD34. In all patients, recurrence of disease occurred after corneal surgery. When transfected in cultured cells, the PDGFRB variants conferred a constitutive activity to the receptor in the absence of its ligand and were sensitive to the tyrosine kinase inhibitor imatinib. The variants can both be classified as likely pathogenic regarding the American College of Medical Genetics and Genomics classification criteria. Conclusions: We describe 4 cases of corneal myofibromatosis caused by novel PDGFRB variants with autosomal dominant transmission. Imatinib sensitivity in vitro suggests perspectives for targeted therapy preventing recurrences in the future. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

GestaltMatcher Database - A global reference for the facial phenotypic variability of rare human diseases.

Dysmorphologists sometimes encounter challenges in recognizing disorders due to phenotypic variability influenced by factors such as age and ethnicity. Moreover, the performance of Next Generation Phenotyping Tools such as GestaltMatcher is dependent on the diversity of the training set. Therefore, we developed GestaltMatcher Database (GMDB) - a global reference for the phenotypic variability of rare diseases that complies with the FAIR-principles. We curated dysmorphic patient images and metadata from 2,224 publications, transforming GMDB into an online dynamic case report journal. To encourage clinicians worldwide to contribute, each case can receive a Digital Object Identifier (DOI), making it a citable micro-publication. This resulted in a collection of 2,312 unpublished images, partly with longitudinal data. We have compiled a collection of 10,189 frontal images from 7,695 patients representing 683 disorders. The web interface enables gene- and phenotype-centered queries for registered users (https://db.gestaltmatcher.org/). Despite the predominant European ancestry of most patients (59%), our global collaborations have facilitated the inclusion of data from frequently underrepresented ethnicities, with 17% Asian, 4% African, and 6% with other ethnic backgrounds. The analysis has revealed a significant enhancement in GestaltMatcher performance across all ethnic groups, incorporating non-European ethnicities, showcasing a remarkable increase in Top-1-Accuracy by 31.56% and Top-5-Accuracy by 12.64%. Importantly, this improvement was achieved without altering the performance metrics for European patients. GMDB addresses dysmorphology challenges by representing phenotypic variability and including underrepresented groups, enhancing global diagnostic rates and serving as a vital clinician reference database.

GestaltMatcher Database - A global reference for facial phenotypic variability in rare human diseases.

The most important factor that complicates the work of dysmorphologists is the significant phenotypic variability of the human face. Next-Generation Phenotyping (NGP) tools that assist clinicians with recognizing characteristic syndromic patterns are particularly challenged when confronted with patients from populations different from their training data. To that end, we systematically analyzed the impact of genetic ancestry on facial dysmorphism. For that purpose, we established the GestaltMatcher Database (GMDB) as a reference dataset for medical images of patients with rare genetic disorders from around the world. We collected 10,980 frontal facial images - more than a quarter previously unpublished - from 8,346 patients, representing 581 rare disorders. Although the predominant ancestry is still European (67%), data from underrepresented populations have been increased considerably via global collaborations (19% Asian and 7% African). This includes previously unpublished reports for more than 40% of the African patients. The NGP analysis on this diverse dataset revealed characteristic performance differences depending on the composition of training and test sets corresponding to genetic relatedness. For clinical use of NGP, incorporating non-European patients resulted in a profound enhancement of GestaltMatcher performance. The top-5 accuracy rate increased by +11.29%. Importantly, this improvement in delineating the correct disorder from a facial portrait was achieved without decreasing the performance on European patients. By design, GMDB complies with the FAIR principles by rendering the curated medical data findable, accessible, interoperable, and reusable. This means GMDB can also serve as data for training and benchmarking. In summary, our study on facial dysmorphism on a global sample revealed a considerable cross ancestral phenotypic variability confounding NGP that should be counteracted by international efforts for increasing data diversity. GMDB will serve as a vital reference database for clinicians and a transparent training set for advancing NGP technology.

Carrier testing for autosomal recessive disorders: a look at current practice in Germany.

Counseling recurrence risks for monogenic disorders is one of the mainstays of human genetics. However, in practice, consultations concerning autosomal recessive disorders exceed the simple conveyance of a 25 % recurrence risk for future offspring. Medical geneticists should be aware of the multifaceted way in which autosomal recessive disorders can pose a diagnostic and counseling challenge in their daily lives and of the pitfalls they might encounter. Although the intentional or incidental detection of carrier states for autosomal recessive diseases happens more and more frequently, our current practice when clarifying their associated reproductive risks remains unsystematic and often subjectively guided. We question whether the approach of focusing on small recurrence risks for a single familial disease with extensive single-gene tests in the partner of a known carrier truly addresses the counseling needs of a couple seeking preconceptional genetic advice. Different perspectives between patients and medical practitioners (or between different medical practitioners) on "acceptable risks" or the extent to which such risks must be minimized raise the question of whether existing professional guidelines need to be clarified.

Long-term outcome of arthroscopic debridement of massive irreparable rotator cuff tears.

OBJECTIVES: To evaluate the clinical and radiographic outcome of low-demand patients with massive rotator cuff tears undergoing arthroscopic debridement in mid- and long-term follow-up, as well as the rate of conversion to reverse shoulder arthroplasty. METHODS: We performed a retrospective analysis of 19 patients with a mean age at surgery of 68 years (range, 55-80 years) from a previously described consecutive cohort and after a mean follow up of 47 month (FU1) and 145 month (FU2). The functional outcome was evaluated with the VAS score, the American Shoulder and Elbow Surgeons (ASES) score, and the age- and gender-adjusted Constant (aCS) score. The radiographic outcome was classified according to the Hamada classification. Non-parametric analyses were carried out with the Mann-Whitney U for independent samples and the Wilcoxon signed-rank test for related samples. RESULTS: Five patients (26%) developed symptomatic cuff tear arthropathy and underwent reverse shoulder arthroplasty after a mean time of 63 months (range, 45-97 months). These patients were excluded from further analyses. The mean VAS score of the remaining 14 patients at FU1 was significantly lower compared to preoperatively (P = .041), while there were no significant differences between the VAS score at FU1 and FU2 (P = 1.0). The ASES score of the affected shoulder at FU1 was significantly higher compared to prior to surgery (P = .028), while there were no significant differences between the scores of the affected shoulder between FU1 and FU2 (P = .878). While the ASES score of the contralateral shoulder at FU1 was significantly higher than the score of the affected shoulder (P = .038), there were no significant differences in the ASES scores of the affected and the healthy shoulder at FU2 (P = .575). The evaluation of the aCS produced similar results. A progression of the Hamada grade was documented in 6 patients. CONCLUSIONS: Arthroscopic debridement is a safe and valid option for low-demand middle-age or elderly patients with symptomatic massive rotator cuff tears, leading to a significant pain relief and significantly improved functional outcome at mid- and long-term follow up. However, about a quarter of the patients in our cohort had to undergo reverse shoulder arthroplasty due to symptomatic cuff tear arthropathy. Furthermore, some of the remaining patients continued to undergo radiographic progression. This might be due to the natural history of their disease and/or the surgical procedure, and the clinical relevance of this finding should be evaluated in further studies.

The adult phenotype of Schaaf-Yang syndrome.

BACKGROUND: MAGEL2-associated Schaaf-Yang syndrome (SHFYNG, OMIM #615547, ORPHA: 398069), which was identified in 2013, is a rare disorder caused by truncating variants of the paternal copy of MAGEL2, which is localized in the imprinted region on 15q11.2q13. The phenotype of SHFYNG in childhood partially overlaps with that of the well-established Prader-Willi syndrome (PWS, OMIM #176270). While larger numbers of younger individuals with SHFYNG have been recently published, the phenotype in adulthood is not well established. We recruited 7 adult individuals (aged 18 to 36) with molecularly confirmed SHFYNG and collected data regarding the clinical profile including eating habits, sleep, behavior, personal autonomy, psychiatric abnormalities and other medical conditions, as well as information about the respective phenotypes in childhood. RESULTS: Within our small cohort, we identified a range of common features, such as disturbed sleep, hypoactivity, social withdrawal and anxiety, but also noted considerable differences at the level of personal autonomy and skills. Behavioral problems were frequent, and a majority of individuals displayed weight gain and food-seeking behavior, along with mild intellectual disability or borderline intellectual function. Classical symptoms of SHFYNG in childhood were reported for most individuals. CONCLUSION: Our findings indicate a high variability of the functional abilities and social participation of adults with SHFYNG. A high prevalence of obesity within our cohort was notable, and uncontrollable food intake was a major concern for some caregivers. The phenotypes of PWS and SHFYNG in adulthood might be more difficult to discern than the phenotypes in childhood. Molecular genetic testing for SHFYNG should therefore be considered in adults with the suspected diagnosis of PWS, if testing for PWS has been negative.