Familial epilepsy with auditory features (FEAF), previously known as autosomal-dominant lateral temporal lobe epilepsy (ADLTE) is a genetically heterogeneous syndrome, clinically characterized by focal seizures with prominent auditory symptoms. It is inherited with autosomal-dominant pattern with reduced penetrance (about 70%). Sporadic epilepsy with auditory features cases are more frequent and clinically indistinguishable from familial cases. One causal gene, MICAL-1, encodes MICAL-1, an intracellular multi-domain enzyme that is an important regulator of filamentous actin (F-actin) structures. Pathogenic variants in MICAL-1 account for approximately 7% of FEAF families. Here, we describe a de novo MICAL-1 pathogenic variant, p.Arg915Cys, in a sporadic case, an affected 21-year-old Italian man with no family history of epilepsy. Genetic testing was performed in the patient and his parents, using a next-generation sequencing panel. In cell-based assay, this variant significantly increased MICAL-1 oxidoreductase activity, which likely resulted in dysregulation of F-actin organization. This finding provides further support for a gain-of-function effect underlying MICAL-1-mediated epilepsy pathogenesis, as previously seen with other pathogenic variants. Furthermore, the case study provides evidence that de novo MICAL-1 pathogenic variants can occur in sporadic cases with epilepsy with auditory feature (EAF). PLAIN LANGUAGE SUMMARY: In this study, we report a new MICAL-1 pathogenic variant in a patient without family history for epilepsy, not inherited from his parents. MICAL-1 is a protein with enzymatic activity that reorganizes the structure of the cell. We proved the pathological effect of this variant by testing its enzymatic activity and found an increase of this activity. This result suggests that non-familial cases should be tested to find novel pathogenic variants in this gene.

BACKGROUND: Tuberous sclerosis complex (TSC) is a rare genetic disease that affects multiple organs and affects the quality of life. Mutations in TSC1 and TSC2 genes are causing dysregulations in the mammalian target of the rapamycin (mTOR) pathway, inducing mostly benign but also malignant tumors, including renal cell carcinoma (RCC). The diagnosis of TSC, based on established clinical and genetic criteria, is essential for the optimal surveillance and management of patients.
METHODS: With the current report, we present the case of two sisters who were consequently diagnosed with early-stage chromophobe-like RCC, possibly familial given their young age. The younger sister also had a previous diagnosis of differentiated thyroid carcinoma, for which she had been treated properly. Genetic testing of both revealed the same heterozygous TSC2 variant that is currently regarded as a variant of unknown significance, while both patients did not fulfill the clinical criteria for the diagnosis of TSC. Owing to these data, we opted to manage and surveil both sisters as TSC patients, while we also considered the specific TSC2 variant to be pathogenic - but of low penetrance - based on clinical judgment and functional analyses. Furthermore, we discussed the implementation of mTOR inhibitors for the treatment of TSC complications.
CONCLUSIONS: As novel pathogenic variants of TSC genes are constantly being explored, the identification of TSC variants of unknown significance in combination with absent clinical diagnostic criteria cannot exclude a TSC diagnosis. We support the implementation of clinical judgment in assisting the diagnosis of TSC, as well as the enrollment of patients in clinical trials due to the rarity of the disease.

BACKGROUND: Gaucher disease (GD) is an autosomal recessive lysosomal storage disease. The disease develops due to glucocerebrosidase enzyme deficiency caused by biallelic pathogenic variants in the glucosylceramidase beta 1 (GBA1) gene, which encodes the glucocerebrosidase enzyme. The GBA1 gene is located at chromosomal location 1q22 and consists of 11 exons. In this article, we report a novel pathogenic variant in the GBA1 gene.
METHODS: A 32-year-old female patient with no known chronic disease was admitted with complaints of weakness, bone pain, and abdominal pain. Her evaluation included hepatosplenomegaly, thrombocytopenia, osteoporosis, and anemia. The clinical suspicion of Gaucher disease was confirmed by glucocerebrosidase enzyme level and genetic testing. In her family screening, her sister also had hepato-splenomegaly, osteoporosis, thrombocytopenia, and anemia. Both sisters had no neurological symptoms. As a result of GBA1 gene sequence analysis in two of our patients, a missense variant was detected in the c.593C>A homozygous genotype. This variant has not been reported in any previously published case.
CONCLUSIONS: In this case report, we aimed to contribute to the literature by reporting a new novel pathogenic variant in the GBA1 gene leading to type 1 Gaucher disease that has not been described before.

PTEN hamartoma tumor syndrome (PHTS), is a spectrum of disorders caused by mutations of PTEN, in which non-cancerous growths, called hamartomas, develop in different areas of the body, often including the oral mucosa. PHTS also implies a recognized increased risk of malignancies, as PTEN is a tumor suppressor gene capable of inhibiting progression of several cancers. One of the main and most common clinical manifestation of PHTS are gingival overgrowths presenting as warty lumps. The current study describes patients with gingival or mucosal enlargements leading to the diagnosis of PHTS associated to novel PTEN pathogenic variants. Patients referred to us for gingival lumps suggestive of PHTS associated overgrowths were submitted to genetic analysis in the PTEN gene. Two related and two unrelated patients were investigated. PTEN novel pathogenic variant was found in all of them. Two patients also fulfilled diagnostic criteria of Cowden syndrome (CS). Mucocutaneous lesions, and particularly diffuse gingival overgrowths, are both early and major clinical signs revealing a potential diagnosis of PHTS. Further genetic and clinical assessments are needed in order to confirm and clarify the diagnosis within the PHTS spectrum, including, among others, the CS. A correct interpretation of oral clinical features potentially associated to PHTS is mandatory for diagnosis and a surgical approach can be useful just in case of impairment of periodontal health or for aesthetic needs. The increased risk of malignancies associated to PHTS makes a correct diagnosis pivotal to set up an appropriate lifelong surveillance, aiming at secondary cancer prevention.

UNASSIGNED: Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive disorder, typically caused by biallelic pathogenic variants in the lipoprotein lipase (LPL) gene. Lipoprotein lipase, encoded by the LPL gene, catalyzes the hydrolysis of triglycerides, and its deficiency or dysfunction can lead to chylomicronemia and potentially fatal recurrent acute pancreatitis.
UNASSIGNED: Here, we report an Asian child with FCS due to compound heterozygous LPL variants. The 4-year-old patient presented with splenomegaly and severe hypertriglyceridemia, specifically chylomicronemia which resulted in abnormal coagulation measured by a turbidity-based assay. Based on the clinical features and family history, the diagnosis of FCS was suspected, and confirmed by the identification of compound heterozygous variants in the LPL gene (c.461A>G; p.His154Arg and c.788T>A; p.Leu263Gln) in the patient, inheriting one from each parent. According to the clinical and genetic findings, the patient was diagnosed with FCS. In vitro experimental validation found that the LPL p.H154R variant reduced the expression of lipoprotein lipase and decreased its lipolytic activity, while the LPL p.L263Q variant mainly impaired its lipolytic activity.
UNASSIGNED: FCS was molecularly diagnosed using whole exome sequencing in the case presented. When interpreting abnormal coagulation profiles measured by turbidity-based assay, the possibility of lipemic blood (or chylomicronemia) should be considered and the presence of this phenomenon might indicate the diagnosis of FCS. In vitro experiments showed that the two LPL variants impaired lipoprotein lipase expression and/or function making them likely to be pathogenic.

Pathogenic variants in GEMIN4 contribute to a hereditary disorder characterized by neurodevelopmental features, microcephaly, cataracts, and renal abnormalities (known as NEDMCR). To date, only two homoallelic variations have been linked to the disease. Moreover, clinical features associated with the variants have not been fully elucidated yet. Here, we identified a novel variant in GEMIN4 (NM_015721:exon2:c.440A>G:p.His147Arg) in two siblings from a consanguineous Saudi family by using whole exome sequencing followed by Sanger sequence verification. We comprehensively investigated the patients\' clinical features, including brain imaging and electroencephalogram findings, and compared their phenotypic characteristics with those of previously reported cases. In silico prediction and structural modeling support that the p.His147Arg variant is pathogenic.

Progressive familial intrahepatic cholestasis (PFIC) is an autosomal recessive inherited disease that accounts for 10%-15% childhood cholestasis and could lead to infant disability or death. There are three well-established types of PFIC (1-3), caused by mutations in the ATP8B1, ABCB11, and ABCB4 genes. Biallelic pathogenic variants in the tight junction protein 2 gene (TJP2) were newly reported as a cause for PFIC type 4; however, only a limited number of patients and undisputable variants have been reported for TJP2, and the underlying mechanism for PFIC 4 remains poorly understood. To explore the diagnostic yield of TJP2 analysis in suspected PFIC patients negative for the PFIC1-3 mutation, we designed a multiplex polymerase chain reaction-based next-generation sequencing method to analyze TJP2 gene variants in 267 PFIC patients and identified biallelic rare variants in three patients, including three known pathogenic variants and two novel variants in three patients. By using CRISPR-cas9 technology, we demonstrated that TJP2 c.1202A > G was pathogenic at least partially by increasing the expression and nuclear localization of TJP2 protein. With the minigene assay, we showed that TJP2 c.2668-11A > G was a new pathogenic variant by inducing abnormal splicing of TJP2 gene and translation of prematurely truncated TJP2 protein. Furthermore, knockdown of TJP2 protein by siRNA technology led to inhibition of cell proliferation, induction of apoptosis, dispersed F-actin, and disordered microfilaments in LO2 and HepG2celles. Global gene expression profiling of TJP2 knockdown LO2 cells and HepG2 cells identified the dysregulated genes involved in the regulation of actin cytoskeleton. Microtubule cytoskeleton genes were significantly downregulated in TJP2 knockdown cells. The results of this study demonstrate that TJP2 c.1202A > G and TJP2 c.2668-11A > G are two novel pathogenic variants and the cytoskeleton-related functions and pathways might be potential molecular pathogenesis for PFIC.

Pathogenic variants in the mitochondrial tyrosyl-tRNA synthetase gene (YARS2) were associated with myopathy, lactic acidosis, and sideroblastic anemia (MLASA). However, patients can present mitochondrial myopathy, with exercise intolerance and muscle weakness, leading from mild to lethal phenotypes. Genes implicated in mtDNA replication were studied by Next Generation Sequencing (NGS) and whole exome sequence with the TruSeq Rapid Exome kit (Illumina, San Diego, CA, USA). Mitochondrial protein translation was studied following the Sasarman and Shoubridge protocol and oxygen consumption rates with Agilent Seahorse XF24 Analyzer Mitostress Test, (Agilent, Santa Clara, CA, USA). We report two siblings with two novel compound heterozygous pathogenic variants in YARS2 gene: a single nucleotide deletion in exon 1, c.314delG (p.(Gly105Alafs*4)), which creates a premature stop codon in the amino acid 109, and a single nucleotide change in exon 5 c.1391T>C (p.(Ile464Thr)), that cause a missense variant in amino acid 464. We demonstrate the pathogenicity of these new variants associated with reduced YARS2 mRNA transcript, reduced mitochondrial protein translation and dysfunctional organelle function. These pathogenic variants are responsible for late onset MLASA, herein accompanied by pancreatic insufficiency, observed in both brothers, clinically considered as Pearson\'s syndrome. Molecular study of YARS2 gene should be considered in patients presenting Pearson\'s syndrome characteristics and MLASA related phenotypes.

Traboulsi syndrome is a very rare, syndromic form of ectopia lentis that is potentially sight-threatening at a young age. It is characterized by typical facial, skeletal and ocular signs.
Two siblings, born to consanguineous parents, with a clinical phenotype consistent with Traboulsi syndrome, underwent extensive ophthalmic imaging and exome-based genetic testing. Both were treated with unilateral clear lens extraction via a limbal approach.
Two siblings, one male and one female, presented with systemic and ocular features consistent with Traboulsi syndrome. Lens subluxation was present in all 4fouraffected eyes, and spontaneous subconjunctival bleb formation was detected in one eye. This eye also showed evidence of keratoconus-related corneal thinning. The clinical diagnosis of Traboulsi syndrome was confirmed molecularly. A homozygous, novel, pathogenic nonsense variant was identified in exon 25 of the ASPH gene: c.2181_2183dup, p.(Val727_Trp728insTer). Excellent visual outcomes following clear lens extraction and postoperative rigid gas-permeable contact lens fitting were obtained.
We expanded the genetic spectrum of Traboulsi syndrome with a novel frameshift variant in the ASPH gene. We showed that lensectomy followed by gas-permeable contact lenses is an efficient therapeutic approach to treat lens subluxation in Traboulsi syndrome. However, lifelong follow-up is crucial to avoid (late) postoperative complications.

Tubulinopathies are a group of conditions caused by variants in 6 tubulin genes that present with a spectrum of brain malformations. One of these conditions is TUBB2A-related tubulinopathy. Currently, there are 9 reported individuals with pathogenic variants within the TUBB2A gene, with common manifestations including, but not limited to, global developmental delay, seizures, cortical dysplasia, and dysmorphic corpus callosum. We report 3 patients identified by exome and genome sequencing to have a novel, pathogenic, missense variant in TUBB2A (p.Gly98Arg). They presented similarly with intellectual disability, hypotonia, and global developmental delay and varied with respect to the type of cortical brain malformation, seizure history, diagnosis of autism spectrum disorder, and other features. This case series expands the natural history of TUBB2A-related tubulinopathy while describing the presentation of a novel, pathogenic, missense variant in 3 patients.