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Introduction: Developmental and epileptic encephalopathy 9 (DEE9) is caused by pathogenic variants in the PCDH19 gene. The clinical features include early-onset seizures that are often provoked by fever and display clustered seizures, mild to profound intellectual disability, autistic traits, and behavioral disturbances. DEE9 is characterized by an unusual X-linked pattern where heterozygous females or rarely mosaic hemizygous males are affected, but hemizygous males and homozygous females are asymptomatic. In recent years, an increasing number of female and male patients with PCDH19-related epilepsy and symptoms have been reported. Methods: Here, we report two additional female patients with DEE9 who are siblings. After analyzing karyotype testing results, whole-exome sequencing (WES) was performed for the proband. Then, Sanger sequencing was carried out for proband, her affected sister, and parents. Results: Sequencing results revealed that our two patients had a heterozygous frameshift variant (NM_001184880.2: c.1091delC, p.P364Rfs*4) in the PCDH19 gene. We also reviewed previously reported cases with this mutation in detail. Conclusion: This is the first report of germline mosaicism in the PCDH19 gene in the Iranian population and expanded the phenotypic spectrum of DEE9. Genetic testing has become an effective way of determining the diagnosis. Parental germline mosaicism should be considered when providing genetic counseling for X-linked/autosomal dominant disorders. This report also emphasizes the importance of considering prenatal diagnosis (PND) in such cases. [ABSTRACT FROM AUTHOR]

Background: Niemann-Pick disease type C (NPC) is a rare lysosomal neurovisceral storage disease caused by mutations in the NPC 1 (95%) or NPC2 (5%) genes. The products of NPC1 and NPC2 genes play considerable roles in glycolipid and cholesterol trafficking, which could consequently lead to NPC disease with variable phenotypes displaying a broad spectrum of symptoms. Materials: In the present study 35 Iranian NPC unrelated patients were enrolled. These patients were first analysed by the Filipin Staining test of cholesterol deposits in cells for NPC diagnostics. Genomic DNA was extracted from the samples of peripheral blood leukocytes in EDTA following the manufacturer's protocol. All exon–intron boundaries and coding exons of the NPC1gene were amplified by polymerase chain reaction (PCR) using appropriate sets of primers. Thereafter, the products of PCR were sequenced and analysed using the NCBI database (https://blast.ncbi.nlm.nih.gov/Blast.cgi). The variants were reviewed by some databases including the Human Gene Mutation Database (HGMD) (http://www.hgmd.cf.ac.uk/ac/index.php) and ClinVar (https://www.ncbi.nlm.nih.gov/clinvar (. Moreover, all the variants were manually classified in terms of the American College of Medical Genetics and Genomics (ACMG) guideline. Results: The sequence analysis revealed 20 different variations, 10 of which are new, including one nonsense mutation (c.406C > T); three small deletions, (c.3126delC, c.2920_2923delCCTG, and c.2037delG); and six likely pathogenic missense mutations, (c.542C > A, c.1970G > A, c.1993C > G, c.2821 T > C, c.2872C > G, and c.3632 T > A). Finally, the pathogenicity of these new variants was determined using the ACMG guidelines. Conclusion: The present study aimed to facilitate the prenatal diagnosis of NPC patients in the future. In this regard, we identified 10 novel mutations, and verified that the majority of them occurred in six NPC1 exons (5, 8, 9, 13, 19, and 21), that should be considered with a high priority for Iranian patients' cost-effective evaluation. [ABSTRACT FROM AUTHOR]

• Megaconial congenital muscular dystrophy is related to CHKB gene variants. • Features include delayed gross-motor milestones, autistic features and weakness. • Peripheral arrangements of large mitochondria and central areas devoid of mitochondria. • This report includes eleven different CHKB gene variants included six novel variants. Megaconial congenital muscular dystrophy (OMIM: 602,541) related to CHKB gene mutation is a newly defined rare autosomal recessive disorder, with multisystem involvement presenting from the neonatal period to adolescence. Choline kinase beta, lipid transport enzyme, catalyzes the biosynthesis of phosphatidylcholine and phosphatidylethanolamine, two major components of the mitochondrial membrane, on which respiratory enzyme activities are dependent. CHKB gene variants lead to loss-of-function of choline kinase b and lipid metabolism defects and mitochondrial structural changes. To date, many megaconial congenital muscular dystrophy cases due to CHKB gene variants have been reported worldwide. We describe thirteen Iranian megaconial congenital muscular dystrophy cases related to CHKB gene variants, including clinical presentations, laboratory and muscle biopsy findings, and novel CHKB gene variants. The most common symptoms and signs included intellectual disability, delayed gross-motor developmental milestones, language skills problems, muscle weakness, as well as autistic features, and behavioral problems. Muscle biopsy examination showed the striking finding of peripheral arrangements of large mitochondria in muscle fibers and central sarcoplasmic areas devoid of mitochondria. Eleven different CHKB gene variants including six novel variants were found in our patients. Despite the rarity of this disorder, recognition of the multisystem clinical presentations combined with characteristic findings of muscle histology can properly guide to genetic evaluation of CHKB gene. [ABSTRACT FROM AUTHOR]

Background and Aims: Epilepsy as a common chronic neurological disorder is characterized by recurrent unprovoked seizures. Febrile seizures are the most common type of epilepsy in infants and children. Our aim was the molecular analysis of SCN1A gene in affected Iranian patients with GEFS+ and Dravet syndrome diagnosed clinically to explain genotype−phenotype correlation and exact classification. Methods: The 34 unrelated Iranian families with epilepsy were selected and screened for SCN1A mutations by MLPA, ARMS, and PCR-RFLP confirmed by direct sequencing. Results: MLPA analysis showed normal patterns, but direct sequencing revealed that generally 20/34 (0.588) probands have common reported single nucleotide polymorphisms (SNPs) (p.A1067G; rs2298771) with allelic frequency as 0.706/0.294 in patients and 0.515/0.485 in control group, respectively, for A/G. No significant differences between groups were observed. Moreover, four novel allelic variants as missense substitutions included two new sequence variation (p.F412 I, p.Y1274N) and two previously reported mutations (p.R101G, p.S103G) that were detected in 4/34 probands but not in control groups and other healthy normal family members. Conclusions: Clinical diagnosis could nearly establish the classification, but mutation screening helps clinicians to confirm their data. We found mutation in four probands and confirmed the net diagnosis. Our data suggest that the clinical symptom variations could be also explained, considering the role of modifier genes such as mitochondrial mutations or other genes responsible for drug metabolism pathways including multiple drug resistance family genes (ABCB1) or MTHFR. [Copyright &y& Elsevier]