Biology subjects

Lockhart, P.

Publications and source records attributed to Lockhart, P..

4 recordsLinked to original sources

bioRxiv2026

Calibrated high-throughput electrophysiology enables clinical interpretation of CACNA1G missense variants

ObjectiveAccurate classification of ion channel variants of uncertain significance (VUS) remains a persistent challenge in clinical genomics, limiting diagnostic resolution in neurological disorders. MethodsWe developed a calibrated electrophysiological framework to generate functional evidence for clinical interpretation of CACNA1G variants encoding the low-voltage-activated calcium channel Cav3.1. Functional metrics derived from automated patchclamp recordings were calibrated against benign/likely benign (B/LB) and pathogenic/likely pathogenic (P/LP) reference variants to enable conservative application of ACMG/AMP functional criteria within clinical variant interpretation workflows. ResultsCalibration using 25 B/LB and 16 P/LP CACNA1G variants showed that more than 80% of P/LP variants exhibited reduced current density (CD). Deactivation kinetics ({tau}Deact) provided complementary discriminatory information by identifying gating abnormalities in variants with preserved CD. Application of this dual-metric framework to five VUS identified in Australian patients revealed two variants (Cav3.1-R186Q and R1394Q) with abnormal functional profiles consistent with voltage-sensor perturbation, supporting reassessment as likely pathogenic under ACMG/AMP guidelines. The remaining VUS displayed functional properties overlapping the benign reference distribution. ConclusionThese findings establish a calibrated functional framework for generating electrophysiological evidence that supports clinical interpretation of CACNA1G missense variants under ACMG/AMP guidelines. When applied as external functional evidence, this approach improves resolution of CACNA1G-associated VUS while maintaining conservative standards for variant classification.

neuroscience↗

bioRxiv2020

The DCC receptor regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation

The forebrain hemispheres are predominantly separated during embryogenesis by the interhemispheric fissure (IHF). Radial astroglia remodel the IHF to form a continuous substrate between the hemispheres for midline crossing of the corpus callosum (CC) and hippocampal commissure (HC). DCC and NTN1 are molecules that have an evolutionarily conserved function in commissural axon guidance. The CC and HC are absent in Dcc and Ntn1 knockout mice, while other commissures are only partially affected, suggesting an additional aetiology in forebrain commissure formation. Here, we find that these molecules play a critical role in regulating astroglial development and IHF remodelling during CC and HC formation. Human subjects with DCC mutations display disrupted IHF remodelling associated with CC and HC malformations. Thus, axon guidance molecules such as DCC and NTN1 first regulate the formation of a midline substrate for dorsal commissures prior to their role in regulating axonal growth and guidance across it.

neuroscience↗

bioRxiv2019

Prevalence of RFC1-Mediated Spinocerebellar Ataxia in a United States Ataxia Cohort

ObjectiveRepeat expansions in RFC1 and DAB1 have recently been identified as causing cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) and spinocerebellar ataxia 37 (SCA37), respectively. We evaluated the prevalence of these repeat-expansions in an undiagnosed ataxia cohort from the United States.\n\nMethodsA cohort of 596 patients with undiagnosed familial or sporadic cerebellar ataxia were evaluated at a tertiary referral ataxia center and excluded for common genetic causes of cerebellar ataxia. Patients were then screened for the presence of pathogenic repeat expansions in RFC1 (AAGGG) and DAB1 (ATTTC) using fluorescent repeat primed polymerase chain reaction (RP-PCR). Two additional undiagnosed ataxia cohorts from different centers, totaling 96 and 13 patients respectively, were subsequently screened for RFC1 resulting in a combined 705 subjects tested.\n\nResultsIn the initial cohort, 42 samples were identified with one expanded allele in the RFC1 gene (7.0%), and 9 had two expanded alleles (1.5%). For the additional cohorts, we found 12 heterozygous samples (12.5%) and 7 biallelic samples (7.3%) in the larger cohort, and 1 heterozygous sample (7.7%) and 3 biallelic samples (23%) in the second. In total, 19 patients were identified with biallelic repeat expansions in RFC1 (2.7%). Of these 19 patients, 6 (32%) had a clinical diagnosis of CANVAS, 10 had cerebellar ataxia with neuropathy (53%), and 3 had spinocerebellar ataxia (16%). No patients were identified with expansions in the DAB1 gene.\n\nConclusionIn a large undiagnosed ataxia cohort from the United States, biallelic pathogenic repeat expansion in RFC1 was observed in 2.7%. Testing should be strongly considered in ataxia patients, especially those with CANVAS or neuropathy.

genetics↗

bioRxiv2019

Tracing Autism Traits in Large Multiplex Families to Identify Endophenotypes of the Broader Autism Phenotype

Families comprising many individuals with Autism Spectrum Disorder (ASD) may carry a dominant predisposing mutation. Our aim was to use rigorous phenotyping of the Broader Autism Phenotype (BAP) in large multiplex ASD families to identify endophenotypes of the BAP for future genetic studies. We evaluated ASD/BAP features using standardised tests and a semi-structured interview to assess social, intellectual, executive and adaptive functioning in 109 individuals, including two large multiplex families (Family A: 30; Family B: 34) and an independent sample of small families (n=45). Our protocol identified four psychological endophenotypes of the BAP that were evident in both samples, and showed high sensitivity (97%) and specificity (82%) for individuals classified with the BAP. The patterns of inheritance of these endophenotypes varied in the two large families, supporting their utility for identifying genes in autism.

neuroscience↗