Mutations in RNU7-1 Weaken Secondary RNA Structure, Induce MCP-1 and CXCL10 in CSF, and Result in Aicardi-Goutières Syndrome with Severe End-Organ Involvement

BACKGROUND

Aicardi-Goutières syndrome (AGS) is a type I interferonopathy usually characterized by early-onset neurologic regression. Biallelic mutations in LSM11 and RNU7-1, components of the U7 small nuclear ribonucleoprotein (snRNP) complex, have been identified in a limited number of genetically unexplained AGS cases. Impairment of U7 snRNP function results in misprocessing of replication-dependent histone (RDH) pre-mRNA and disturbance of histone occupancy of nuclear DNA, ultimately driving cGAS-dependent type I interferon (IFN-I) release.

OBJECTIVE

We performed a clinical, genetic, and immunological workup of 3 unrelated patients with uncharacterized AGS.

METHODS

Whole exome sequencing (WES) and targeted Sanger sequencing of RNU7-1 were performed. Primary fibroblasts were used for mechanistic studies. IFN-I signature and STAT1/2 phosphorylation were assessed in peripheral blood. Cytokines were profiled on serum and cerebrospinal fluid (CSF). Histopathology was examined on brain and kidney tissue.

RESULTS

Sequencing revealed compound heterozygous RNU7-1 mutations, resulting in impaired RDH pre-mRNA processing. The 3' stem-loop mutations reduced stability of the secondary U7 snRNA structure. A discrete IFN-I signature in peripheral blood was paralleled by MCP-1 (CCL2) and CXCL10 upregulation in CSF. Histopathological analysis of the kidney showed thrombotic microangiopathy. We observed dysregulated STAT phosphorylation upon cytokine stimulation. Clinical overview of all reported patients with RNU7-1-related disease revealed high mortality and high incidence of organ involvement compared to other AGS genotypes.

CONCLUSIONS

Targeted RNU7-1 sequencing is recommended in genetically unexplained AGS cases. CSF cytokine profiling represents an additional diagnostic tool to identify aberrant IFN-I signaling. Clinical follow-up of RNU7-1-mutated patients should include screening for severe end-organ involvement including liver disease and nephropathy.

De novo FZR1 loss-of-function variants cause developmental and epileptic encephalopathies

FZR1, which encodes the Cdh1 subunit of the anaphase-promoting complex, plays an important role in neurodevelopment by regulating the cell cycle and by its multiple post-mitotic functions in neurons. In this study, evaluation of 250 unrelated patients with developmental and epileptic encephalopathies and a connection on GeneMatcher led to the identification of three de novo missense variants in FZR1. Whole-exome sequencing in 39 patient-parent trios and subsequent targeted sequencing in an additional cohort of 211 patients was performed to identify novel genes involved in developmental and epileptic encephalopathy. Functional studies in Drosophila were performed using three different mutant alleles of the Drosophila homologue of FZR1 fzr. All three individuals carrying de novo variants in FZR1 had childhood-onset generalized epilepsy, intellectual disability, mild ataxia and normal head circumference. Two individuals were diagnosed with the developmental and epileptic encephalopathy subtype myoclonic atonic epilepsy. We provide genetic-association testing using two independent statistical tests to support FZR1 association with developmental and epileptic encephalopathies. Further, we provide functional evidence that the missense variants are loss-of-function alleles using Drosophila neurodevelopment assays. Using three fly mutant alleles of the Drosophila homologue fzr and overexpression studies, we show that patient variants can affect proper neurodevelopment. With the recent report of a patient with neonatal-onset with microcephaly who also carries a de novo FZR1 missense variant, our study consolidates the relationship between FZR1 and developmental and epileptic encephalopathy and expands the associated phenotype. We conclude that heterozygous loss-of-function of FZR1 leads to developmental and epileptic encephalopathies associated with a spectrum of neonatal to childhood-onset seizure types, developmental delay and mild ataxia. Microcephaly can be present but is not an essential feature of FZR1-encephalopathy. In summary, our approach of targeted sequencing using novel gene candidates and functional testing in Drosophila will help solve undiagnosed myoclonic atonic epilepsy or developmental and epileptic encephalopathy cases.

Delineating the neurological phenotype in children with defects in the ECHS1 or HIBCH gene

The neurological phenotype of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) and short-chain enoyl-CoA hydratase (SCEH) defects is expanding and natural history studies are necessary to improve clinical management. From 42 patients with Leigh syndrome studied by massive parallel sequencing, we identified five patients with SCEH and HIBCH deficiency. Fourteen additional patients were recruited through collaborations with other centres. In total, we analysed the neurological features and mutation spectrum in 19 new SCEH/HIBCH patients. For natural history studies and phenotype to genotype associations we also included 70 previously reported patients. The 19 newly identified cases presented with Leigh syndrome (SCEH, n = 11; HIBCH, n = 6) and paroxysmal dystonia (SCEH, n = 2). Basal ganglia lesions (18 patients) were associated with small cysts in the putamen/pallidum in half of the cases, a characteristic hallmark for diagnosis. Eighteen pathogenic variants were identified, 11 were novel. Among all 89 cases, we observed a longer survival in HIBCH compared to SCEH patients, and in HIBCH patients carrying homozygous mutations on the protein surface compared to those with variants inside/near the catalytic region. The SCEH p.(Ala173Val) change was associated with a milder form of paroxysmal dystonia triggered by increased energy demands. In a child harbouring SCEH p.(Ala173Val) and the novel p.(Leu123Phe) change, an 83.6% reduction of the protein was observed in fibroblasts. The SCEH and HIBCH defects in the catabolic valine pathway were a frequent cause of Leigh syndrome in our cohort. We identified phenotype and genotype associations that may help predict outcome and improve clinical management.

De Novo Variants in LMNB1 Cause Pronounced Syndromic Microcephaly and Disruption of Nuclear Envelope Integrity

Lamin B1 plays an important role in the nuclear envelope stability, the regulation of gene expression, and neural development. Duplication of LMNB1, or missense mutations increasing LMNB1 expression, are associated with autosomal-dominant leukodystrophy. On the basis of its role in neurogenesis, it has been postulated that LMNB1 variants could cause microcephaly. Here, we confirm this hypothesis with the identification of de novo mutations in LMNB1 in seven individuals with pronounced primary microcephaly (ranging from -3.6 to -12 SD) associated with relative short stature and variable degree of intellectual disability and neurological features as the core symptoms. Simplified gyral pattern of the cortex and abnormal corpus callosum were noted on MRI of three individuals, and these individuals also presented with a more severe phenotype. Functional analysis of the three missense mutations showed impaired formation of the LMNB1 nuclear lamina. The two variants located within the head group of LMNB1 result in a decrease in the nuclear localization of the protein and an increase in misshapen nuclei. We further demonstrate that another mutation, located in the coil region, leads to increased frequency of condensed nuclei and lower steady-state levels of lamin B1 in proband lymphoblasts. Our findings collectively indicate that de novo mutations in LMNB1 result in a dominant and damaging effect on nuclear envelope formation that correlates with microcephaly in humans. This adds LMNB1 to the growing list of genes implicated in severe autosomal-dominant microcephaly and broadens the phenotypic spectrum of the laminopathies.

Clinical, Biomarker, and Molecular Delineations and Genotype-Phenotype Correlations of Ataxia With Oculomotor Apraxia Type 1

Importance

Ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive cerebellar ataxia due to mutations in the aprataxin gene (APTX) that is characterized by early-onset cerebellar ataxia, oculomotor apraxia, axonal motor neuropathy, and eventual decrease of albumin serum levels.

Objectives

To improve the clinical, biomarker, and molecular delineation of AOA1 and provide genotype-phenotype correlations.

Design, Setting, and Participants

This retrospective analysis included the clinical, biological (especially regarding biomarkers of the disease), electrophysiologic, imaging, and molecular data of all patients consecutively diagnosed with AOA1 in a single genetics laboratory from January 1, 2002, through December 31, 2014. Data were analyzed from January 1, 2015, through January 31, 2016.

Main Outcomes and Measures

The clinical, biological, and molecular spectrum of AOA1 and genotype-phenotype correlations.

Results

The diagnosis of AOA1 was confirmed in 80 patients (46 men [58%] and 34 women [42%]; mean [SD] age at onset, 7.7 [7.4] years) from 51 families, including 57 new (with 8 new mutations) and 23 previously described patients. Elevated levels of α-fetoprotein (AFP) were found in 33 patients (41%); hypoalbuminemia, in 50 (63%). Median AFP level was higher in patients with AOA1 (6.0 ng/mL; range, 1.1-17.0 ng/mL) than in patients without ataxia (3.4 ng/mL; range, 0.8-17.2 ng/mL; P < .01). Decreased albumin levels (ρ = -0.532) and elevated AFP levels (ρ = 0.637) were correlated with disease duration. The p.Trp279* mutation, initially reported as restricted to the Portuguese founder haplotype, was discovered in 53 patients with AOA1 (66%) with broad white racial origins. Oculomotor apraxia was found in 49 patients (61%); polyneuropathy, in 74 (93%); and cerebellar atrophy, in 78 (98%). Oculomotor apraxia correlated with the severity of ataxia and mutation type, being more frequent with deletion or truncating mutations (83%) than with presence of at least 1 missense variant (17%; P < .01). Mean (SD) age at onset was higher for patients with at least 1 missense mutation (17.7 [11.4] vs 5.2 [2.6] years; P < .001).

Conclusions and Relevance

The AFP level, slightly elevated in a substantial fraction of patients, may constitute a new biomarker for AOA1. Oculomotor apraxia may be an optional finding in AOA1 and correlates with more severe disease. The p.Trp279* mutation is the most frequent APTX mutation in the white population. APTX missense mutations may be associated with a milder phenotype.

SPG20 mutation in three siblings with familial hereditary spastic paraplegia

Troyer syndrome (MIM#275900) is an autosomal recessive form of complicated hereditary spastic paraplegia. It is characterized by progressive lower extremity spasticity and weakness, dysarthria, distal amyotrophy, developmental delay, short stature, and subtle skeletal abnormalities. It is caused by deleterious mutations in the SPG20 gene, encoding spartin, on Chromosome 13q13. Until now, six unrelated families with a genetically confirmed diagnosis have been reported. Here we report the clinical findings in three brothers of a consanguineous Moroccan family, aged 24, 17, and 7 yr old, with spastic paraplegia, short stature, motor and cognitive delay, and severe intellectual disability. Targeted exon capture and sequencing showed a homozygous nonsense mutation in the SPG20 gene, c.1369C>T (p.Arg457*), in the three affected boys.

Bi-allelic variants in COL3A1 encoding the ligand to GPR56 are associated with cobblestone-like cortical malformation, white matter changes and cerebellar cysts

BACKGROUND

Collagens are one of the major constituents of the pial membrane, which plays a crucial role in neuronal migration and cortical lamination during brain development. Type III procollagen, the chains of which are encoded by COL3A1, is the ligand of the G protein-coupled receptor 56 (GPR56), also known as adhesion G protein-coupled receptor G1. Bi-allelic mutations in GPR56 give rise to cobblestone-like malformation, white matter changes and cerebellar dysplasia. This report shows that bi-allelic mutations in COL3A1 are associated with a similar phenotype.

METHODS

Exome analysis was performed in a family consisting of two affected and two non-affected siblings. Brain imaging studies of this family and of two previously reported individuals with bi-allelic mutations in COL3A1 were reviewed. Functional assays were performed on dermal fibroblasts.

RESULTS

Exome analysis revealed a novel homozygous variant c.145C>G (p.Pro49Ala) in exon 2 of COL3A1. Brain MRI in the affected siblings as well as in the two previously reported individuals with bi-allelic COL3A1 mutations showed a brain phenotype similar to that associated with mutations in GPR56.

CONCLUSION

Homozygous or compound heterozygous mutations in COL3A1 are associated with cobblestone-like malformation in all three families reported to date. The variability of the phenotype across patients suggests that genetic alterations in distinct domains of type III procollagen can lead to different outcomes. The presence of cobblestone-like malformation in patients with bi-allelic COL3A1 mutations emphasises the critical role of the type III collagen-GPR56 axis and the pial membrane in the regulation of brain development and cortical lamination.

Redefining the MED13L syndrome

Congenital cardiac and neurodevelopmental deficits have been recently linked to the mediator complex subunit 13-like protein MED13L, a subunit of the CDK8-associated mediator complex that functions in transcriptional regulation through DNA-binding transcription factors and RNA polymerase II. Heterozygous MED13L variants cause transposition of the great arteries and intellectual disability (ID). Here, we report eight patients with predominantly novel MED13L variants who lack such complex congenital heart malformations. Rather, they depict a syndromic form of ID characterized by facial dysmorphism, ID, speech impairment, motor developmental delay with muscular hypotonia and behavioral difficulties. We thereby define a novel syndrome and significantly broaden the clinical spectrum associated with MED13L variants. A prominent feature of the MED13L neurocognitive presentation is profound language impairment, often in combination with articulatory deficits.

Refinement of the critical 2p25.3 deletion region: the role of MYT1L in intellectual disability and obesity

PURPOSE

Submicroscopic deletions of chromosome band 2p25.3 are associated with intellectual disability and/or central obesity. Although MYT1L is believed to be a critical gene responsible for intellectual disability, so far no unequivocal data have confirmed this hypothesis.

METHODS

In this study we evaluated a cohort of 22 patients (15 sporadic patients and two families) with a 2p25.3 aberration to further refine the clinical phenotype and to delineate the role of MYT1L in intellectual disability and obesity. In addition, myt1l spatiotemporal expression in zebrafish embryos was analyzed by quantitative polymerase chain reaction and whole-mount in situ hybridization.

RESULTS

Complete MYT1L deletion, intragenic deletion, or duplication was observed in all sporadic patients, in addition to two patients with a de novo point mutation in MYT1L. The familial cases comprise a 6-Mb deletion in a father and his three children and a 5' MYT1L overlapping duplication in a father and his two children. Expression analysis in zebrafish embryos shows specific myt1l expression in the developing brain.

CONCLUSION

Our data strongly strengthen the hypothesis that MYT1L is the causal gene for the observed syndromal intellectual disability. Moreover, because 17 patients present with obesity/overweight, haploinsufficiency of MYT1L might predispose to weight problems with childhood onset.Genet Med 17 6, 460-466.

PRRT2 mutations: exploring the phenotypical boundaries

BACKGROUND

Mutations in the proline-rich transmembrane protein 2 (PRRT2) gene have been identified in patients with benign (familial) infantile convulsions (B(F)IC), infantile convulsions with choreoathetosis (ICCA) and paroxysmal dyskinesias (PDs). However it remains unknown whether PRRT2 mutations are causal in other epilepsy syndromes. After we discovered a PRRT2 mutation in a large family with ICCA containing one individual with febrile seizures (FS) and one individual with West syndrome, we analysed PRRT2 in a heterogeneous cohort of patients with different types of infantile epilepsy.

METHODS

We screened a cohort of 460 patients with B(F)IC or ICCA, fever related seizures or infantile epileptic encephalopathies. All patients were tested for point mutations using direct sequencing.

RESULTS

We identified heterozygous mutations in 16 individuals: 10 familial and 6 sporadic cases. All patients were diagnosed with B(F)IC, ICCA or PD. We were not able to detect mutations in any of the other epilepsy syndromes. Several mutation carriers had learning disabilities and/or impaired fine motor skills later in life.

CONCLUSIONS

PRRT2 mutations do not seem to be involved in the aetiology of FS or infantile epileptic encephalopathies. Therefore B(F)IC, ICCA and PD remain the core phenotypes associated with PRRT2 mutations. The presence of learning disabilities or neuropsychiatric problems in several mutation carriers calls for additional clinical studies addressing this developmental aspect in more detail.

Mate pair sequencing for the detection of chromosomal aberrations in patients with intellectual disability and congenital malformations

Recently, microarrays have replaced karyotyping as a first tier test in patients with idiopathic intellectual disability and/or multiple congenital abnormalities (ID/MCA) in many laboratories. Although in about 14-18% of such patients, DNA copy-number variants (CNVs) with clinical significance can be detected, microarrays have the disadvantage of missing balanced rearrangements, as well as providing no information about the genomic architecture of structural variants (SVs) like duplications and complex rearrangements. Such information could possibly lead to a better interpretation of the clinical significance of the SV. In this study, the clinical use of mate pair next-generation sequencing was evaluated for the detection and further characterization of structural variants within the genomes of 50 ID/MCA patients. Thirty of these patients carried a chromosomal aberration that was previously detected by array CGH or karyotyping and suspected to be pathogenic. In the remaining 20 patients no causal SVs were found and only benign aberrations were detected by conventional techniques. Combined cluster and coverage analysis of the mate pair data allowed precise breakpoint detection and further refinement of previously identified balanced and (complex) unbalanced aberrations, pinpointing the causal gene for some patients. We conclude that mate pair sequencing is a powerful technology that can provide rapid and unequivocal characterization of unbalanced and balanced SVs in patient genomes and can be essential for the clinical interpretation of some SVs.

KCNQ2 encephalopathy: emerging phenotype of a neonatal epileptic encephalopathy

OBJECTIVE

KCNQ2 and KCNQ3 mutations are known to be responsible for benign familial neonatal seizures (BFNS). A few reports on patients with a KCNQ2 mutation with a more severe outcome exist, but a definite relationship has not been established. In this study we investigated whether KCNQ2/3 mutations are a frequent cause of epileptic encephalopathies with an early onset and whether a recognizable phenotype exists.

METHODS

We analyzed 80 patients with unexplained neonatal or early-infantile seizures and associated psychomotor retardation for KCNQ2 and KCNQ3 mutations. Clinical and imaging data were reviewed in detail.

RESULTS

We found 7 different heterozygous KCNQ2 mutations in 8 patients (8/80; 10%); 6 mutations arose de novo. One parent with a milder phenotype was mosaic for the mutation. No KCNQ3 mutations were found. The 8 patients had onset of intractable seizures in the first week of life with a prominent tonic component. Seizures generally resolved by age 3 years but the children had profound, or less frequently severe, intellectual disability with motor impairment. Electroencephalography (EEG) at onset showed a burst-suppression pattern or multifocal epileptiform activity. Early magnetic resonance imaging (MRI) of the brain showed characteristic hyperintensities in the basal ganglia and thalamus that later resolved.

INTERPRETATION

KCNQ2 mutations are found in a substantial proportion of patients with a neonatal epileptic encephalopathy with a potentially recognizable electroclinical and radiological phenotype. This suggests that KCNQ2 screening should be included in the diagnostic workup of refractory neonatal seizures of unknown origin.

Neuromyelitis optica-IgG+ optic neuritis associated with celiac disease and dysgammaglobulinemia: a role for tacrolimus?

We present a pediatric case of recurrent optic neuritis, celiac disease, partial IgA and IgG3 deficiency in the context of anti-aquaporin-4 auto-immunity and familial IgA deficiency with celiac disease. Treatment with tacrolimus was successful in preventing disease relapses. This case stresses the relevance of central nervous system anti-aquaporin-4 auto-immunity in a broader context of immune dysregulation and neuro-immunology.

Early onset collagen VI myopathies: Genetic and clinical correlations

OBJECTIVE

Mutations in the genes encoding the extracellular matrix protein collagen VI (ColVI) cause a spectrum of disorders with variable inheritance including Ullrich congenital muscular dystrophy, Bethlem myopathy, and intermediate phenotypes. We extensively characterized, at the clinical, cellular, and molecular levels, 49 patients with onset in the first 2 years of life to investigate genotype-phenotype correlations.

METHODS

Patients were classified into 3 groups: early-severe (18%), moderate-progressive (53%), and mild (29%). ColVI secretion was analyzed in patient-derived skin fibroblasts. Chain-specific transcript levels were quantified by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), and mutation identification was performed by sequencing of complementary DNA.

RESULTS

ColVI secretion was altered in all fibroblast cultures studied. We identified 56 mutations, mostly novel and private. Dominant de novo mutations were detected in 61% of the cases. Importantly, mutations causing premature termination codons (PTCs) or in-frame insertions strikingly destabilized the corresponding transcripts. Homozygous PTC-causing mutations in the triple helix domains led to the most severe phenotypes (ambulation never achieved), whereas dominant de novo in-frame exon skipping and glycine missense mutations were identified in patients of the moderate-progressive group (loss of ambulation).

INTERPRETATION

This work emphasizes that the diagnosis of early onset ColVI myopathies is arduous and time-consuming, and demonstrates that quantitative RT-PCR is a helpful tool for the identification of some mutation-bearing genes. Moreover, the clinical classification proposed allowed genotype-phenotype relationships to be explored, and may be useful in the design of future clinical trials.

Rating scales for dystonia in cerebral palsy: reliability and validity

AIM

This study investigated the reliability and validity of the Barry-Albright Dystonia Scale (BADS), the Burke-Fahn-Marsden Movement Scale (BFMMS), and the Unified Dystonia Rating Scale (UDRS) in patients with bilateral dystonic cerebral palsy (CP).

METHOD

Three raters independently scored videotapes of 10 patients (five males, five females; mean age 13 y 3 mo, SD 5 y 2 mo, range 5-22 y). One patient each was classified at levels I-IV in the Gross Motor Function Classification System and six patients were classified at level V. Reliability was measured by (1) intraclass correlation coefficient (ICC) for interrater reliability, (2) standard error of measurement (SEM) and smallest detectable difference (SDD), and (3) Cronbach's alpha for internal consistency. Validity was assessed by Pearson's correlations among the three scales used and by content analysis.

RESULTS

Moderate to good interrater reliability was found for total scores of the three scales (ICC: BADS=0.87; BFMMS=0.86; UDRS=0.79). However, many subitems showed low reliability, in particular for the UDRS. SEM and SDD were respectively 6.36% and 17.72% for the BADS, 9.88% and 27.39% for the BFMMS, and 8.89% and 24.63% for the UDRS. High internal consistency was found. Pearson's correlations were high. Content validity showed insufficient accordance with the new CP definition and classification.

INTERPRETATION

Our results support the internal consistency and concurrent validity of the scales; however, taking into consideration the limitations in reliability, including the large SDD values and the content validity, further research on methods of assessment of dystonia is warranted.

SPG15 is the second most common cause of hereditary spastic paraplegia with thin corpus callosum

OBJECTIVE

Hereditary spastic paraplegias (HSPs) are very heterogeneous inherited neurodegenerative disorders. Our group recently identified ZFYVE26 as the gene responsible for one of the clinical and genetic entities, SPG15. Our aim was to describe its clinical and mutational spectra.

METHODS

We analyzed all exons of SPG15/ZFYVE26 gene by direct sequencing in a series of 60 non-SPG11 HSP subjects with associated mental or MRI abnormalities, including 30 isolated cases. The clinical data were collected through the SPATAX network.

RESULTS

We identified 13 novel truncating mutations in ZFYVE26, 12 of which segregated at the homozygous or compound heterozygous states in 8 new SPG15 families while 1 was found at the heterozygous state in a single family. Two of 3 splice site mutations were validated on mRNA of 2 patients. The SPG15 phenotype in 11 affected individuals was characterized by early onset HSP, severe progression of the disease, and mental impairment dominated by cognitive decline. Thin corpus callosum and white matter hyperintensities were MRI hallmarks of the disease in this series.

CONCLUSIONS

The mutations are truncating, private, and distributed along the entire coding sequence of ZFYVE26, which complicates the analysis of this gene in clinical practice. In our series of patients with hereditary spastic paraplegia-thin corpus callosum, the largest analyzed so far, SPG15 was the second most frequent form (11.5%) after SPG11. Both forms share similar clinical and imaging presentations with very few distinctions, which are, however, insufficient to infer the molecular diagnosis when faced with a single patient.

Encephalocraniocutaneous lipomatosis accompanied by the formation of bone cysts: Harboring clues to pathogenesis?

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadically occurring neurocutaneous disorder characterized by ocular anomalies, mainly choristomas; by skin lesions consisting of hairless fatty tissue nevi (nevus psiloliparus), focal dermal hypoplasia, alopecia, and periocular skin tags; and by CNS anomalies, including intracranial and spinal lipomas and often mental retardation and seizures. Here, we report on three boys with ECCL with typical abnormalities of the eyes, skin and brain and, in addition, coarctation of the aorta. All three children developed multiple cystic bone lesions, which progressively spread throughout the skeleton in Patient 1 and was shown histologically to be non-ossifying fibromas in Patient 2. We hypothesize that ECCL may be caused by mosaicism for a mutated gene involved in benign mesenchymal tumors and in vasculogenesis.

Folate receptor autoantibodies and spinal fluid 5-methyltetrahydrofolate deficiency in Rett syndrome

Rett syndrome was associated with low cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF) in 42-50% of European patients whereas approximately 93% of the patients from North-America had a normal CSF 5MTHF status. We determined the CSF folate status in Rett patients living in North- and South-Western Europe and measured serum folate receptor (FR) autoantibodies of the blocking type to explain the reduced folate transport across the choroid plexus. Irrespective of their MECP2 genotype and despite normal plasma folate values, 14 of 33 Rett patients (42%) had low CSF folate levels. Blocking FR autoantibodies were found in 8 of the Rett patients (24%), 6 of whom had low CSF folate levels. FR autoimmunity was primarily found within the group of Rett patients with low CSF folate status with a higher incidence in North-Western Europe. In Rett patients from North-America 74 of 76 girls had higher folate values in both serum and CSF than European patients. The food folate fortification in North-America may account for the higher folate levels and may prevent CFD in these Rett patients. FR autoimmunity occurred predominantly in Rett patients from North-Western Europe and may contribute to cerebral folate deficiency (CFD).

Anti-proliferative properties of prenylated flavonoids from hops (Humulus lupulus L.) in human prostate cancer cell lines

Chalcones xanthohumol (X) and desmethylxanthohumol (DMX), present in hops (Humulus lupulus L.), and the corresponding flavanones isoxanthohumol (IX, from X), 8-prenylnaringenin (8-PN, from DMX), and 6-prenylnaringenin (6-PN, from DMX), have been examined in vitro for their anti-proliferative activity on human prostate cancer cells PC-3 and DU145. X proved to be the most active compound in inhibiting the growth of the cell lines with IC50 values of 12.3+/-1.1 microM for DU145 and 13.2+/-1.1 microM for PC-3. 6-PN was the second most active growth inhibitor, particularly in PC-3 cells (IC50 of 18.4+/-1.2 microM). 8-PN, a highly potent phytoestrogen, exhibited pronounced anti-proliferative effects on PC-3 and DU145 (IC50 of 33.5+/-1.0 and 43.1+/-1.2 microM, respectively), and IX gave comparable activities (IC50 of 45.2+/-1.1 microM for PC-3 and 47.4+/-1.1 microM for DU145). DMX was the least active compound. It was evidenced for the first time that this family of prenylated flavonoids from hops effectively inhibits proliferation of prostate cancer cells in vitro.

MFN2 mutation distribution and genotype/phenotype correlation in Charcot-Marie-Tooth type 2

Mutations in mitofusin 2 (MFN2) have been reported in Charcot-Marie-Tooth type 2 (CMT2) families. To study the distribution of mutations in MFN2 we screened 323 families and isolated patients with distinct CMT phenotypes. In 29 probands, we identified 22 distinct MFN2 mutations, and 14 of these mutations have not been reported before. All mutations were located in the cytoplasmic domains of the MFN2 protein. Patients presented with a classical but rather severe CMT phenotype, since 28% of them were wheelchair-dependent. Some had additional features as optic atrophy. Most patients had an early onset and severe disease status, whereas a smaller group experienced a later onset and milder disease course. Electrophysiological data showed in the majority of patients normal to slightly reduced nerve conduction velocities with often severely reduced amplitudes of the compound motor and sensory nerve action potentials. Examination of sural nerve specimens showed loss of large myelinated fibres and degenerative mitochondrial changes. In patients with a documented family history of CMT2 the frequency of MFN2 mutations was 33% indicating that MFN2 mutations are a major cause in this population.

Dominant and recessive COL6A1 mutations in Ullrich scleroatonic muscular dystrophy

In this study, we characterized five Ullrich scleroatonic muscular dystrophy patients (two Italians, one Belgian, and two Turks) with a clinical phenotype showing different degrees of severity, all carrying mutations localized in COL6A1. We sequenced the three entire COL6 complementary DNA. Three of five patients have recessive mutations: two patients (P1and P3) have homozygous single-nucleotide deletions, one in exon 9 and one in exon 22; one patient (P2) has a homozygous single-nucleotide substitution leading to a premature termination codon in exon 31. The nonsense mutation of P2 also causes a partial skipping of exon 31 with the formation of a premature termination codon in exon 32 in 15% of the total COL6A1 messenger RNA. The remaining two patients carry a heterozygous glycine substitution in exons 9 and 10 inside the triple-helix region; both are dominant mutations because the missense mutations are absent in the DNA of their respective parents. As for the three homozygous recessive mutations, the apparently healthy consanguineous parents all carry a heterozygous mutated allele. Here, for the first time, we report a genotype-phenotype correlation demonstrating that heterozygous glycine substitutions in the triple-helix domain of COL6A1 are dominant and responsible for a milder Ullrich scleroatonic muscular dystrophy phenotype, and that recessive mutations in COL6A1 correlate with more severe clinical and biochemical Ullrich scleroatonic muscular dystrophy phenotypes.

Perinatal cortical infarction within middle cerebral artery trunks

AIM

To define neonatal pial middle cerebral artery infarction.

METHODS

A retrospective study was made of neonates in whom focal arterial infarction had been detected ultrasonographically. A detailed study was made of cortical middle cerebral artery infarction subtypes.

RESULTS

Forty infarctions, with the exception of those in a posterior cerebral artery, were detected ultrasonographically over a period of 10 years. Most were confirmed by computed tomography or magnetic resonance imaging. Factor V Leiden heterozygosity was documented in three. The onset was probably antepartum in three, and associated with fetal distress before labour in one. There were 19 cases of cortical middle cerebral artery stroke. The truncal type (n=13) was more common than complete (n = 5) middle cerebral artery infarction. Of six infarcts in the anterior trunk, four were in term infants and five affected the right hemisphere. Clinical seizures were part of the anterior truncal presentation in three. One of these infants, with involvement of the primary motor area, developed a severe motor hemisyndrome. The Bayley Mental Developmental Index was above 80 in all of three infants tested with anterior truncal infarction. Of seven patients with posterior truncal infarction, six were at or near term. Six of these lesions were left sided. Clinical seizures were observed in three. A mild motor hemisyndrome developed in at least three of these infants due to involvement of parieto-temporal non-primary cortex.

CONCLUSIONS

Inability to differentiate between truncal and complete middle cerebral artery stroke is one of the explanations for the reported different outcomes. Severe motor hemisyndrome can be predicted from neonatal ultrasonography on the basis of primary motor cortex involvement. Clinical seizures were recognised in less than half of the patients with truncal infarction; left sided presentation was present in the posterior, but not the anterior truncal type of infarction. Asphyxia is a rare cause of focal arterial infarction.