Search

Disruption of genes within the HNRNP gene family has been observed in neurodevelopmental and neurodegenerative diseases. The HNRNP-Related Neurodevelopmental Disorders (HNRNP-RNDDs), while each unique, have been recently described with similar clinical and molecular features across variation in several genes. However, the phenotypic information on these patients is still lacking. In this case series we aim to describe the phenotypes that are associated with SYNCRIP-Related Neurodevelopmental Disorder (SYNCRIP-RNDD). We describe in depth ten novel individuals and one previously published individual with mostly de novo and predicted damaging variants in SYNCRIP, consistent with a diagnosis of SYNCRIP-RNDD. We also describe previously published patients, many of which are from large cohort studies, as well as individuals from patient databases. Here, we expand the phenotype of SYNCRIP-RNDD beyond a generic neurodevelopmental disorder to a variable syndrome consisting of mild to borderline developmental delay/intellectual disability, speech and language delay, behavioral differences such as autism spectrum disorder, structural brain anomalies, hypotonia, and seizures. Inconsistent dysmorphic features were also observed, with the few recurrent findings including long eyelashes, mildly deep-set eyes, prominent ears, and thin or thick lips. This study increases our understanding of SYNCRIP-RNDD, as well as HNRNP-RNDDs broadly.

Summary: Autism spectrum disorder (ASD) is diagnosed three to four times more frequently in males than in females. Genetic studies of rare variants support a female protective effect (FPE) against ASD. However, sex differences in common inherited genetic risk for ASD are less studied, particularly within families. Leveraging the Danish iPSYCH resource, we found siblings of female ASD cases (n = 1,707) had higher rates of ASD than siblings of male ASD cases (n = 6,270; p

BackgroundThe genetic architecture of psychotic disorders is complex, with hundreds of genetic risk loci contributing to a polygenic model of disease. Overlap in the genetics of psychotic disorders and brain measures has been found in European populations, but has not been explored in populations of African ancestry. The aim of this study was to determine whether a relationship exists between a schizophrenia-derived PRS and (i) methamphetamine associated psychosis (MAP), and (ii) brain structural measures, in a South African population.MethodsThe study sample consisted of three participant groups: 31 individuals with MAP, 48 with apsychotic methamphetamine dependence, and 49 healthy controls. Using PRSice, PRS was generated for each of the participants with GWAS summary statistics from the Psychiatric Genomics Consortium Schizophrenia working group (PGC-SCZ2) as the discovery dataset. Regression analyses were performed to determine associations of PRS, with diagnosis, whole brain, and regional gray and white matter measures.ResultsSchizophrenia-derived PRS did not significantly predict MAP diagnosis. After correction for multiple testing, no significant associations were found between PRS and brain measures across all groups.DiscussionThe lack of significant associations here may indicate that the study is underpowered, that brain volumes in MAP are due to factors other than polygenic risk for schizophrenia, or that PRS derived from a largely European discovery set has limited utility in individuals of African ancestry. Larger studies, that include diverse populations, and more nuanced brain measures, may help elucidate the relationship between schizophrenia-PRS, brain structural changes, and psychosis.ConclusionThis research presents the first PRS study to investigate shared genetic effects across psychotic disorders and brain structural measures in an African population. Ancestrally comparable discovery datasets may be useful for future African genetic research.

Mutations in the parkin gene are the most common cause of early-onset Parkinson’s disease (PD). Parkin, an E3 ubiquitin ligase, is involved in respiratory chain function, mitophagy, and mitochondrial dynamics. Human cellular models with parkin null mutations are particularly valuable for investigating the mitochondrial functions of parkin. However, published results reporting on patient-derived parkin-mutant fibroblasts have been inconsistent. This study aimed to functionally compare parkin-mutant fibroblasts from PD patients with wild-type control fibroblasts using a variety of assays to gain a better understanding of the role of mitochondrial dysfunction in PD. To this end, dermal fibroblasts were obtained from three PD patients with homozygous whole exon deletions in parkin and three unaffected controls. Assays of mitochondrial respiration, mitochondrial network integrity, mitochondrial membrane potential, and cell growth were performed as informative markers of mitochondrial function. Surprisingly, it was found that mitochondrial respiratory rates were markedly higher in the parkin-mutant fibroblasts compared to control fibroblasts (p = 0.0093), while exhibiting more fragmented mitochondrial networks (p=0.0304). Moreover, cell growth of the parkin-mutant fibroblasts was significantly higher than that of controls (p=0.0001). These unanticipated findings are suggestive of a compensatory mechanism to preserve mitochondrial function and quality control in the absence of parkin in fibroblasts, which warrants further investigation.