A syndromic neurodevelopmental disorder caused by rare variants in PPFIA3.

PPFIA3 encodes the protein-tyrosine phosphatase, receptor-type, F-polypeptide-interacting-protein-alpha-3 (PPFIA3), which is a member of the LAR-protein-tyrosine phosphatase-interacting-protein (liprin) family involved in synapse formation and function, synaptic vesicle transport, and presynaptic active zone assembly. The protein structure and function are evolutionarily well conserved, but human diseases related to PPFIA3 dysfunction are not yet reported in OMIM. Here, we report 20 individuals with rare PPFIA3 variants (19 heterozygous and 1 compound heterozygous) presenting with developmental delay, intellectual disability, hypotonia, dysmorphisms, microcephaly or macrocephaly, autistic features, and epilepsy with reduced penetrance. Seventeen unique PPFIA3 variants were detected in 18 families. To determine the pathogenicity of PPFIA3 variants in vivo, we generated transgenic fruit flies producing either human wild-type (WT) PPFIA3 or five missense variants using GAL4-UAS targeted gene expression systems. In the fly overexpression assays, we found that the PPFIA3 variants in the region encoding the N-terminal coiled-coil domain exhibited stronger phenotypes compared to those affecting the C-terminal region. In the loss-of-function fly assay, we show that the homozygous loss of fly Liprin-α leads to embryonic lethality. This lethality is partially rescued by the expression of human PPFIA3 WT, suggesting human PPFIA3 function is partially conserved in the fly. However, two of the tested variants failed to rescue the lethality at the larval stage and one variant failed to rescue lethality at the adult stage. Altogether, the human and fruit fly data reveal that the rare PPFIA3 variants are dominant-negative loss-of-function alleles that perturb multiple developmental processes and synapse formation.

A novel approach in pediatric telegenetic services: geneticist, pediatrician and genetic counselor team.

PurposeOur aim was to improve access to genetic services in an underserved region by developing a collaborative telegenetic service delivery model with a pediatrician, medical geneticist, and genetics counselor (GC).MethodsProtocols for the evaluation of common genetic indications were developed. Patients referred with indications suggestive of a syndromic etiology were scheduled to see the geneticist directly via telegenetics. Other patients were scheduled to see the pediatrician and GC in person before follow-up with the geneticist if indicated. Patients seen by the geneticist and/or pediatrician/GC were enumerated and the next available appointment was tracked. Patient satisfaction surveys were conducted.ResultsOf the 265 patients evaluated during the study period, 116 (44%) were evaluated by a pediatrician and GC in person first, after which 82 (71% of those evaluated) required further follow-up with the geneticist. The next available appointment with a pediatrician and GC never exceeded 6 weeks, while new appointments with a geneticist ranged from 3 to 9 months. All patients reported high satisfaction with this genetic service model.ConclusionThe pediatrician/GC clinic provides a model of collaborative care that is a medical home neighbor and exemplifies the integration of genetics into primary care. The telegenetics clinic offers a viable solution to providing competent and convenient access to a geneticist for patients in chronically underserved regions.

Alu-mediated deletion of PIGL in a Patient with CHIME syndrome.

CHIME syndrome is a rare autosomal recessive neuroectodermal disorder associated with biallelic mutations in PIGL. To date, six molecularly confirmed cases of CHIME syndrome have been reported. Here, we report the seventh patient with biallelic PIGL mutations associated with CHIME syndrome and describe the first characterization of an intragenic deletion in PIGL. Our characterization of the deletion breakpoint junction demonstrated that the breakpoints occurred within Alu repeats and the deletion was most likely mediated by a microhomology event. Analysis of PIGL genomic sequences for repetitive elements demonstrated that Alu repeats represent ∼34% of its intronic sequence, suggesting that the genomic architecture may predispose the gene to disease-causing copynumber changes. Taken together, these findings indicate that patients with a clinical diagnosis of CHIME syndrome and a single identifiable mutation in PIGL warrant further investigation for copynumber changes involving PIGL.

McArdle Disease Presenting With Muscle Pain in a Teenage Girl: The Role of Whole-Exome Sequencing in Neurogenetic Disorders.

We present the case of a young woman with worsening attacks of muscle pain and rhabdomyolysis beginning at age 14. Initial metabolic testing and electromyography revealed findings of a nonspecific myopathy. Diagnostic options were discussed among the members of a neurogenetics clinic team. Whole-exome sequencing was selected as a first tier test. This testing revealed a known disease causing mutation in the PYGM gene consistent with McArdle disease. We discuss the decision to use whole-exome sequencing in diagnostics and the rationale for making this our choice as a first-level test modality.

A newborn with complex skeletal abnormalities, joint contractures, and bilateral corneal clouding with sclerocornea.

A newborn presented to genetics with complex skeletal abnormalities, joint contractures, and bilateral corneal clouding with sclerocornea. The patient survived for 8 months before succumbing to respiratory failure. Exome sequencing revealed a compound heterozygous mutation in theB3GALT6gene. Mutations in this gene have been associated with both Ehlers- Danlos syndrome, progeroid type 2 and spondyloepimetaphyseal dysplasia with joint laxity type 1. These diagnoses encompass the skeletal and joint findings. Our patient expands the phenotype of these diagnoses, as anterior segment eye anomalies have not been described with either syndrome, and he is much more profoundly affected. Interestingly, our patient fits the description of a rare genetic disease referred to as Al-Gazali syndrome, for which the genetic cause is unknown.