We present the findings of a Whole Exome Sequencing in a 2-year-old boy, conceived via In Vitro Fertilization with donor sperm, who suffers from an undiagnosed neurological syndrome. The following heterozygous variant in the EPHA4 gene was identified and classified as likely pathogenic: c.1655_1656, p.(Ser552CysfsTer23). Subsequent segregation analysis showed that the variant was not inherited from the mother and the sperm donor is not accessible for genetic testing. The presented results can further expand upon the genetic variants considered when diagnosing complex neurological syndromes and shows the importance of access to biological samples from donor banks in genetically ambiguous cases.

Background: Pharmacoresistant epilepsy represents 30-40% of cases with intractable epilepsy in children, and up to 20% of adult cases. Various cerebral lesions can lead to drug-resistant focal epilepsy. They are medically refractory but the complete surgical resection correlates with good outcome.

Туберозна склероза комплекс (ТСК) е автозомно доминантно заболяване, характеризиращо се с типчни кожни прояви и образуване на множество тумори в различни органи, главно в централната нервна система. Пациентите с туберозна склерозаса най-често с изява на значителен неврологичен дефицит, включително припадъци, аутизъм и интелектуални увреждания, появяващи се в различни периоди от живота. Заболяването се причинява от мутацията на един от двата туморни супресорни гена, TSC1 или TSC2, водещи до нарушение в mTor-киназния път, оттам и до нарушения в клетъчната миграция, пролиферация и диференциация, които са в основата на туморогенезата при ТСК. В няколко големи проучвания са изследвани генотип-фенотипните корелации със значим доказателствен материал по отношение на характерната клинична изява и протичането на заболяването в зависимост от мутацията в един от двата гена - значително по-тежък фенотип при пациенти с TSC2 мутация, спрямо такива с мутация в TSC1 гена. Целта на настоящата публикация е да се направи актуален преглед на досега известните клинико-генетични данни, както и да се представи българския опит при 58 деца и техните фамилии с ТСК.

Церебелитите са енцефалити, най-често остри, и по-рядко подостри или хронични, с изява на церебеларен синдром, характерни са за детската възраст. Оcтрите церебелити се диагностицират при остро възникнал дискоординационен синдром (атаксия с промени в походката, нистагъм, тремор, дизартрия и хипотония), както и екстрацеребеларни синдроми като фебрилитет, главоболие, повръщане. Причиняват се от вируси /(Varicella Zoster Virus (VZV), морбилен, паротитен и хепатитен А, Epstein-Barr, Coxsackie и Западно-нилски вирус), рядко от бактерии (Borrelia Burgdorferi при Лаймска болест) или са с автоимунна етиопатогенеза при автоимунните енцефалити с основна изява на атаксия и стволова симптоматика. В някои случаи заболяването е животозастрашаващо поради малкомозъчен оток, хидроцефалия и притискане на мозъчния ствол. При острите церебелити е необходимо своевременно и точно диагностициране и лечение, както и разграничаване от острата церебеларна атаксия (ОЦA), която бързопреходна и с благоприятна прогноза. ОЦA се характеризира с нарушение на координацията на тялото и на крайниците, успоредно с наличиено на нистагъм, замаяност и световъртеж, възможни са нарушения на слуха, главоболие. Характерна е за детската възраст в хода на различни вирусни инфекции, но са възможни и други невъзпалителни причини като малкомозъчен кръвоизлив, травма, интоксикация, дефицит на витамин В12, В1 и Е, малкомозъчен тумор, мигрена с мозъчностволова аура, бенигнен пароксизмален световъртеж, мозъчни тумори. Представят се литературни данни за особености на клинични, лабораторни, невроизобразяващи и електрофизиологични изследвания за остър церебелит (ОЦ) и остра цебебеларна атаксия (OЦА) и собствени случаи с остър церебелит с преходен церебеларен мутизъм и патологичен пароксизмален смях и страх, вкл. с остра вътрешна хидроцефалия, налагаща декомпресия, както и остър дисеминиран енцефалит (ОДЕМ) с основна изява на атаксия.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the development of hamartomas localized in various tissues which can occur in the skin, brain, kidney and other organs. TSC is caused by mutations in the TSC1 and TSC2 genes. Here we report the results from the first molecular testing of 16 Bulgarian patients and one Romanian patient in whom we found six novel mutations: four in the TSC2 gene, of which one is nonsense, two frame shift and one large deletion of 16 exons; and two in the TSC1 gene, one nonsense and other frame shift. In addition, we detected 10 previously reported mutations; some of which are described only once in the literature. Our data is similar to the previous studies with exception of the larger number of TSC1 mutations than that reported in the literature data. In total, 40% (4/10) of the mutation in the TSC2 gene are located in the GTPase-activating protein domain, while 50% (3/6) are in the TSC1 gene and clustered in exon 15. All the cases represent the typical clinical symptoms and meet the clinical criteria for TSC diagnosis. In 35% of our cases the family history was positive. Our results add novel findings in the genetic heterogeneity and pathogenesis of TSC. The genetic heterogeneity might correlate to the clinical variability among the TSC-affected families, which makes the genetic counselling a real challenge.

Neurofibromatosis (NF) is a clinically heterogeneous autosomal dominant disorder. Three distinct forms have been identified: neurofibromatosis type 1 (NF1), type 2 (NF2) and schwannomatosis. In the present study, we report clinical and genetic findings in the NF1 and NF2 genes in a cohort of 27 Bulgarian patients, with 18 cases (67%) genetically verified. Both NF1 and NF2 genes were screened by Sanger sequencing on DNA samples. The Sanger negative samples were screened by Multiplex Ligation-dependent Probe Amplification (MLPA) for deletions and duplications. The results from genetic testing revealed three novel mutations and fifteen previously reported ones (13 in the NF1 gene and 2 in the NF2 gene). The novel variants in the NF1 gene are a splice site mutation c.4725-1G>A, a small deletion of five bases c.823delATCTT, p.Leu275ValfsTer14, and a single base duplication c.6547dupC, p.Arg2183ProfsTer11. The novel splice site mutation is manifested by multiple “café au lait” macules and neurofibromas. Both novel out of frame mutations were found in patients with multiple “café au lait” spots and focal epilepsy. A segmental neurofibromatosis (S NF1 ) is restricted to one or more body segments. Here we present a case with S NF1 caused by a somatic deletion of exons 1 to 12 of the NF1 gene which is manifested by multiple neurofibromas in the right hand. Two nonsense mutations are found in the NF2 gene. Our study adds three novel mutations to the NF1 mutation spectra and contributes to the clinical-genetic NF1-characterization. Here we report strikingly different phenotypic spectra caused by the same mutation in a single family. Our findings contribute to the genotype- phenotype correlations which are difficult to establish, due to the extremely complex NF phenotype being a combination of clinical features.

Objective Ring chromosome 20 syndrome (R20) has an almost constant association with refractory epilepsy and intellectual and behavioral disabilities. Though early diagnosis is usually difficult and rarely made, Particular electroclinical patterns have been found to be very helpful for the R20 diagnosis that is usually difficult and rarely early made. Here, we present the clinical, EEG and cytogenetic correlations in three patients with R20. Methods Three patients, aged 17, 13 and 4 years, respectively, were studied by video-EEG monitoring (VEEG) for drug-resistant seizures. Brain MRI was normal; standard EEGs showed anterior epileptiform activity with one-sided predominance, correlating to some ictal clinical features; intellectual and behavioral problems increased with age and disease course. VEEG as a part of presurgical evaluation was considered because of drug-resistant epilepsy. Results All three patients presented an electroclinical pattern consistent with frontal epilepsy. They also had subclinical or "subtle" clinical episodes, both awake and in sleep, corresponding to nonconvulsive status epilepticus (NCSE). The epilepsy started earlier (age 3 years) in the youngest patient with more severe epilepsy. The seizures started later (age 7 and 9 years, respectively) and were rarer in the older patients, who also showed mild cognitive and behavioral disability. Due to the particular electroclinical picture R20 was suspected and cytogenetic analysis was performed. It revealed R20 mosaic karyotype, at 10%, 25% and 40%, respectively. Conclusion The presented cases show again that the diagnosis of R20 syndrome is usually delayed and is based on the very helpful and characteristic for the syndrome electroclinical NCSE pattern and the overall "frontal" seizure appearance. Our cases add further evidence for the genotype-phenotype correlation in the syndrome, since the degree of mosaicism reflects the age of epilepsy onset, the severity and refractoriness of the seizures, and the severity of the associated intellectual and behavioral disabilities. Ring chromosome 20 syndrome (R20) has an almost constant association with refractory epilepsy and intellectual and behavioral disabilities. Though early diagnosis is usually difficult and rarely made, Particular electroclinical patterns have been found to be very helpful for the R20 diagnosis that is usually difficult and rarely early made. Here, we present the clinical, EEG and cytogenetic correlations in three patients with R20. Three patients, aged 17, 13 and 4 years, respectively, were studied by video-EEG monitoring (VEEG) for drug-resistant seizures. Brain MRI was normal; standard EEGs showed anterior epileptiform activity with one-sided predominance, correlating to some ictal clinical features; intellectual and behavioral problems increased with age and disease course. VEEG as a part of presurgical evaluation was considered because of drug-resistant epilepsy. All three patients presented an electroclinical pattern consistent with frontal epilepsy. They also had subclinical or "subtle" clinical episodes, both awake and in sleep, corresponding to nonconvulsive status epilepticus (NCSE). The epilepsy started earlier (age 3 years) in the youngest patient with more severe epilepsy. The seizures started later (age 7 and 9 years, respectively) and were rarer in the older patients, who also showed mild cognitive and behavioral disability. Due to the particular electroclinical picture R20 was suspected and cytogenetic analysis was performed. It revealed R20 mosaic karyotype, at 10%, 25% and 40%, respectively. The presented cases show again that the diagnosis of R20 syndrome is usually delayed and is based on the very helpful and characteristic for the syndrome electroclinical NCSE pattern and the overall "frontal" seizure appearance. Our cases add further evidence for the genotype-phenotype correlation in the syndrome, since the degree of mosaicism reflects the age of epilepsy onset, the severity and refractoriness of the seizures, and the severity of the associated intellectual and behavioral disabilities.

Aims: Epilepsy in patients with PCDH19 mutations is often pharmacoresistant, there is less data on drug therapy strategies. As PCDH19 mutations are increasingly diagnosed, the spectrum of the known appearance expanded. We therefore investigated the clinical course and the effectiveness of antiepileptic drugs in these patients.

GAT-1, encoded by SLC6A1, is one of the major gamma-aminobutyric acid (GABA) transporters in the brain and is responsible for re-uptake of GABA from the synapse. In this study, targeted resequencing of 644 individuals with epileptic encephalopathies led to the identification of six SLC6A1 mutations in seven individuals, all of whom have epilepsy with myoclonic-atonic seizures (MAE). We describe two truncations and four missense alterations, all of which most likely lead to loss of function of GAT-1 and thus reduced GABA re-uptake from the synapse. These individuals share many of the electrophysiological properties of Gat1-deficient mice, including spontaneous spike-wave discharges. Overall, pathogenic mutations occurred in 6/160 individuals with MAE, accounting for similar to 4% of unsolved MAE cases.