Mutations in plasticity-related-gene-1 (PRG-1) protein contribute to hippocampal seizure susceptibility and modify epileptic phenotype.

The Phospholipid Phosphatase Related 4 gene (PLPPR4,  *607813) encodes the Plasticity-Related-Gene-1 (PRG-1) protein. This cerebral synaptic transmembrane-protein modulates cortical excitatory transmission on glutamatergic neurons. In mice, homozygous Prg-1 deficiency causes juvenile epilepsy. Its epileptogenic potential in humans was unknown. Thus, we screened 18 patients with infantile epileptic spasms syndrome (IESS) and 98 patients with benign familial neonatal/infantile seizures (BFNS/BFIS) for the presence of PLPPR4 variants. A girl with IESS had inherited a PLPPR4-mutation (c.896C > G, NM_014839; p.T299S) from her father and an SCN1A-mutation from her mother (c.1622A > G, NM_006920; p.N541S). The PLPPR4-mutation was located in the third extracellular lysophosphatidic acid-interacting domain and in-utero electroporation (IUE) of the Prg-1p.T300S construct into neurons of Prg-1 knockout embryos demonstrated its inability to rescue the electrophysiological knockout phenotype. Electrophysiology on the recombinant SCN1Ap.N541S channel revealed partial loss-of-function. Another PLPPR4 variant (c.1034C > G, NM_014839; p.R345T) that was shown to result in a loss-of-function aggravated a BFNS/BFIS phenotype and also failed to suppress glutamatergic neurotransmission after IUE. The aggravating effect of Plppr4-haploinsufficiency on epileptogenesis was further verified using the kainate-model of epilepsy: double heterozygous Plppr4-/+|Scn1awt|p.R1648H mice exhibited higher seizure susceptibility than either wild-type, Plppr4-/+, or Scn1awt|p.R1648H littermates. Our study shows that a heterozygous PLPPR4 loss-of-function mutation may have a modifying effect on BFNS/BFIS and on SCN1A-related epilepsy in mice and humans.

Update of penetrance estimates in Birt-Hogg-Dubé syndrome.

BACKGROUND: Birt-Hogg-Dubé (BHD) syndrome is a rare genetic syndrome caused by pathogenic or likely pathogenic germline variants in the FLCN gene. Patients with BHD syndrome have an increased risk of fibrofolliculomas, pulmonary cysts, pneumothorax and renal cell carcinoma. There is debate regarding whether colonic polyps should be added to the criteria. Previous risk estimates have mostly been based on small clinical case series. METHODS: A comprehensive review was conducted to identify studies that had recruited families carrying pathogenic or likely pathogenic variants in FLCN. Pedigree data were requested from these studies and pooled. Segregation analysis was used to estimate the cumulative risk of each manifestation for carriers of FLCN pathogenic variants. RESULTS: Our final dataset contained 204 families that were informative for at least one manifestation of BHD (67 families informative for skin manifestations, 63 for lung, 88 for renal carcinoma and 29 for polyps). By age 70 years, male carriers of the FLCN variant have an estimated 19% (95% CI 12% to 31%) risk of renal tumours, 87% (95% CI 80% to 92%) of lung involvement and 87% (95% CI 78% to 93%) of skin lesions, while female carriers had an estimated 21% (95% CI 13% to 32%) risk of renal tumours, 82% (95% CI 73% to 88%) of lung involvement and 78% (95% CI 67% to 85%) of skin lesions. The cumulative risk of colonic polyps by age 70 years old was 21% (95% CI 8% to 45%) for male carriers and 32% (95% CI 16% to 53%) for female carriers. CONCLUSIONS: These updated penetrance estimates, based on a large number of families, are important for the genetic counselling and clinical management of BHD syndrome.

[Not a pneumothorax again! Birt-Hogg-Dubé syndrome: a case report]. / "Nicht schon wieder ein Pneumothorax" ­ Fallbericht Birt-Hogg-Dubé-Syndrom.

Case discussion of a 40-year-old male patient with a history of recurrent pneumothoraces due to Birt-Hogg-Dubé syndrome. In addition to conservative treatment of a pneumothorax on the left side, a subtotal parietal pleurectomy on the right side was performed after recurrence of a pneumothorax 6 years later. CT of the thorax showed high-grade structural remodelling of the lung parenchyma with cystic lung lesions on both sides with a diameter of up to 7.5 cm. After exclusion of alpha-1 antitrypsin deficiency, underlying immunological disease, unremarkable family and occupational history, Birt-Hogg-Dubé syndrome was suspected based on the morphological distribution pattern of the cystic lung lesions. Genetic examination helped detect a heterozygous pathogenic variant in the FLCN gene, namely c.1294_1298del;p.(Ser432Argfs*22). Birt-Hogg-Dubé syndrome is a rare genetic disorder clinically characterized by pulmonary cysts, fibrofolliculomas of the skin and occurrence of clustered renal tumors. In particular, the increased risk of renal malignancies and the risk of spontaneous pneumothoraces underlines the importance of early diagnosis and screening of affected patients and their families.

Remarkable effect of transdermal nicotine in children with CHRNA4-related autosomal dominant sleep-related hypermotor epilepsy.

OBJECTIVE: Autosomal dominant sleep-related hypermotor epilepsy (ADSHE) is characterized by hypermotor seizures and may be caused by gain-of-function mutations affecting the nicotinic acetylcholine receptor (nAChR). Benefit from nicotine consumption has been reported in adult patients with this disorder. For the first time, the effect of transdermal nicotine is evaluated in children. METHODS: Transdermal nicotine was applied to three boys, two aged 10 years (7 mg/24 h) and one six years (3.5 mg/24 h). Autosomal dominant sleep-related hypermotor epilepsy was caused by the p.S280F-CHRNA4 (cholinergic receptor, nicotinic, alpha polypeptide 4) mutation. The children suffered from frequent, persistent nocturnal seizures and had developed educational and psychosocial problems. Seizure frequency and cognitive and behavioral parameters were assessed before and after treatment. RESULTS: A striking seizure reduction was reported soon after treatment onset. Hypermotor seizures disappeared; only sporadic arousals, sometimes with minor motor elements, were observed. Psychometric testing documented improvement in cognitive domains such as visuospatial ability, processing speed, memory, and some areas of executive functions. SIGNIFICANCE: Nicotine appears to be a mechanistic treatment for this specific disorder, probably because of desensitization of the mutated receptors. It may control seizures resistant to conventional drugs for epilepsy and impact socioeducational function in children. This mode of precision therapy should receive more attention and should be available to more patients with uncontrolled CHRNA4-related ADSHE across the age span.

Identification of tetragametic human chimerism by routine DNA profiling.

Chimerism in humans is defined as the presence of two genetically different cell lines within the same organism. It is usually an acquired condition that is restricted to certain tissues and can be explained by therapeutic interventions such as blood transfusion or the transplantation of allogenic hematopoietic cells. Implications of such patients for forensic DNA testing have been described in the literature. In some rare cases, true inherited chimerism is observed. This so called tetragametic chimerism occurs via the fertilization of the two ova by two spermatozoa, followed by the fusion of early embryos and the development of an organism with intermingled cell lines. Such examples have been found in mice and other mammalian species including humans. We describe a phenotypically normal woman in whom tetragametic chimerism (46,XX/46,XX) was unexpectedly identified by STR typing during routine DNA profiling. Cytogenetic analysis proved to be a valuable tool for both independent confirmation and direct visualization of the two coexisting cell lines.

A fluorescence in situ hybridization-based screen allows rapid detection of adverse cytogenetic alterations in patients with acute myeloid leukemia.

In adult acute myeloid leukemia (AML), the karyotype of the leukemic cell is among the strongest prognostic factors. The Medical Research Council (MRC) and the European LeukemiaNet (ELN) classifications distinguish between favorable, intermediate and adverse cytogenetic risk patients who differ in their treatment response and overall survival. Conventional cytogenetic analyses are a mandatory component of AML diagnostics but they are time-consuming; therefore, therapeutic decisions in elderly patients are often delayed. We investigated whether a screening approach using a panel of seven fluorescence in situ hybridization (FISH) probes would allow rapid identification of adverse chromosomal changes. In a cohort of 334 AML patients, our targeted FISH screening approach identified 80% of adverse risk AML patients with a specificity of 99%. Incorporating FISH screening into diagnostic workup has the potential to accelerate risk stratification and treatment selection, particularly in older patients. This approach may allow therapeutic decisions more quickly, which benefits both patients and physicians and might save costs.

Birt-Hogg-Dubé-Syndrom: ein zu selten diagnostiziertes erbliches Tumorsyndrom.

Das Birt-Hogg-Dubé-Syndrom (BHD-Syndrom, eigentlich Hornstein-Knickenberg- Syndrom) ist ein autosomal dominant erbliches Tumorsyndrom, welches durch Mutationen im FLCN-Gen auf Chromosom 17 verursacht wird. Patienten mit BHD-Syndrom können altersabhängig verschiedene Symptome zeigen, deren Ausprägung auch innerhalb einer Familie unterschiedlich schwer sein kann. Ein frühes Symptom sind basal betonte Lungenzysten, welche Ursache wiederholter Spontanpneumothoraces sein können. Die Mehrheit der Patienten (> 90 %) entwickelt im mittleren Lebensalter zahlreiche Fibrofollikulome vor allem im Gesicht und am Oberkörper. Für die Prognose entscheidend ist eine gezielte Tumorvorsorge, da ein Lebenszeitrisiko von 12-34 % für benigne und maligne Nierentumoren besteht. Die Nierentumoren beim BHD-Syndrom können verschiedenen histologischen Subgruppen angehören, wobei multifokale, auch bilaterale Hybridtumoren mit chromophoben und onkozytären Anteilen häufig sind. Die frühzeitige Diagnosestellung ebenso wie die langfristige Betreuung von Familien mit BHD-Syndrom erfordern eine interdisziplinäre Zusammenarbeit.

Birt-Hogg-Dubé syndrome: an underdiagnosed genetic tumor syndrome.

Birt-Hogg-Dubé syndrome (BHD, also referred to as Hornstein-Knickenberg syndrome) is an autosomal dominant tumor syndrome caused by mutations in the FLCN gene located on chromosome 17. Depending on their age, patients with BHD may exhibit various clinical signs and symptoms. Disease severity can vary greatly among members of the same family. Early symptoms include basal lung cysts, which can lead to recurrent spontaneous pneumothoraces. The majority of patients (> 90 %) develop multiple fibrofolliculomas, especially on the face and upper trunk, in the second or third decade of life. Given the 12-34 % lifetime risk of developing benign or malignant renal tumors, targeted screening programs are prognostically crucial. While these renal tumors may belong to various histological subtypes, common variants include multifocal - sometimes bilateral - chromophobe and oncocytic hybrid tumors. Early diagnosis and adequate long-term care of families with BHD require interdisciplinary cooperation.

Cellular and extracellular miRNAs are blood-compartment-specific diagnostic targets in sepsis.

Septic shock is a common medical condition with a mortality approaching 50% where early diagnosis and treatment are of particular importance for patient survival. Novel biomarkers that serve as prompt indicators of sepsis are urgently needed. High-throughput technologies assessing circulating microRNAs represent an important tool for biomarker identification, but the blood-compartment specificity of these miRNAs has not yet been investigated. We characterized miRNA profiles from serum exosomes, total serum and blood cells (leukocytes, erythrocytes, platelets) of sepsis patients by next-generation sequencing and RT-qPCR (n = 3 × 22) and established differences in miRNA expression between blood compartments. In silico analysis was used to identify compartment-specific signalling functions of differentially regulated miRNAs in sepsis-relevant pathways. In septic shock, a total of 77 and 103 miRNAs were down- and up-regulated, respectively. A majority of these regulated miRNAs (14 in serum, 32 in exosomes and 73 in blood cells) had not been previously associated with sepsis. We found a distinctly compartment-specific regulation of miRNAs between sepsis patients and healthy volunteers. Blood cellular miR-199b-5p was identified as a potential early indicator for sepsis and septic shock. miR-125b-5p and miR-26b-5p were uniquely regulated in exosomes and serum, respectively, while one miRNA (miR-27b-3p) was present in all three compartments. The expression of sepsis-associated miRNAs is compartment-specific. Exosome-derived miRNAs contribute significant information regarding sepsis diagnosis and survival prediction and could serve as newly identified targets for the development of novel sepsis biomarkers.

Nocturnal frontal lobe epilepsy caused by a mutation in the GATOR1 complex gene NPRL3.

Mutations in NPRL3, one of three genes that encode proteins of the mTORC1-regulating GATOR1 complex, have recently been reported to cause cortical dysplasia with focal epilepsy. We have now analyzed a multiplex epilepsy family by whole exome sequencing and identified a frameshift mutation (NM_001077350.2; c.1522delG; p.E508Rfs*46) within exon 13 of NPRL3. This truncating mutation causes an epilepsy phenotype characterized by early childhood onset of mainly nocturnal frontal lobe epilepsy. The penetrance in our family was low (three affected out of six mutation carriers), compared to families with either ion channel- or DEPDC5-associated familial nocturnal frontal lobe epilepsy. The absence of apparent structural brain abnormalities suggests that mutations in NPRL3 are not necessarily associated with focal cortical dysplasia but might be able to cause epilepsy by different, yet unknown pathomechanisms.