A Novel p.Leu(381)Phe Mutation in Presenilin 1 is Associated with Very Early Onset and Unusually Fast Progressing Dementia as well as Lysosomal Inclusions Typically Seen in Kufs Disease

Whole exome sequencing in a family with suspected dominant Kufs disease identified a novel Presenilin 1 mutation p.Leu(381)Phe in three brothers who, along with their father, developed progressive dementia and motor deficits in their early 30s. All affected relatives had unusually rapid disease progression (on average 3.6 years from disease onset to death). In silico analysis of mutation p.Leu(381)Phe predicted more detrimental effects when compared to the common Presenilin 1 mutation p.Glu(280)Ala. Electron microscopy study of peripheral fibroblast cells of the proband showed lysosomal inclusions typical for Kufs disease. However his brain autopsy demonstrated typical changes of Alzheimer disease

Mutations in the Gene DNAJC5 Cause Autosomal Dominant Kufs Disease in a Proportion of Cases: Study of the Parry Family and 8 Other Families

Background: The Neuronal Ceroid Lipofuscinoses (NCL) comprise at least nine progressive neurodegenerative genetic disorders. Kufs disease, an adult-onset form of NCL may be recessively or dominantly inherited. Our study aimed to identify genetic mutations associated with autosomal dominant Kufs disease (ADKD). Methodology and Principal Findings We have studied the family first reported with this phenotype in the 1970s, the Parry family. The proband had progressive psychiatric manifestations, seizures and cognitive decline starting in her mid 20s. Similarly affected relatives were observed in seven generations. Several of the affected individuals had post-mortem neuropathological brain study confirmatory for NCL disease. We conducted whole exome sequencing of three affected family members and identified a pLeu116del mutation in the gene DNAJC5, which segregated with the disease phenotype. An additional eight unrelated affected individuals with documented autosomal dominant or sporadic inheritance were studied. All had diagnostic confirmation with neuropathological studies of brain tissue. Among them we identified an additional individual with a p.Leu115Arg mutation in DNAJC5. In addition, a pAsn477Ser change in the neighboring gene PRPF6, a gene previously found to be associated with retinitis pigmentosa, segregated with the ADKD phenotype. Interestingly, two individuals of the Parry family did report visual impairment. Conclusions: Our study confirmed the recently reported association of DNAJC5 mutations with ADKD in two out of nine well-defined families. Sequence changes in PRPF6 have not been identified in other unrelated cases. The association of vision impairment with the expected PRPF6 dysfunction remains possible but would need further clinical studies in order to confirm the co-segregation of the visual impairment with this sequence change

De novo mutations of KIAA2022 in females cause intellectual disability and intractable epilepsy

Background Mutations in the KIAA2022 gene have been reported in male patients with X-linked intellectual disability, and related female carriers were unaffected. Here, we report 14 female patients who carry a heterozygous de novo KIAA2022 mutation and share a phenotype characterised by intellectual disability and epilepsy. Methods Reported females were selected for genetic testing because of substantial developmental problems and/or epilepsy. X-inactivation and expression studies were performed when possible. Results All mutations were predicted to result in a frameshift or premature stop. 12 out of 14 patients had intractable epilepsy with myoclonic and/or absence seizures, and generalised in 11. Thirteen patients had mild to severe intellectual disability. This female phenotype partially overlaps with the reported male phenotype which consists of more severe intellectual disability, microcephaly, growth retardation, facial dysmorphisms and, less frequently, epilepsy. One female patient showed completely skewed X-inactivation, complete absence of RNA expression in blood and a phenotype similar to male patients. In the six other tested patients, X-inactivation was random, confirmed by a non-significant twofold to threefold decrease of RNA expression in blood, consistent with the expected mosaicism between cells expressing mutant or normal KIAA2022 alleles. Conclusions Heterozygous loss of KIAA2022 expression is a cause of intellectual disability in females. Compared with its hemizygous male counterpart, the heterozygous female disease has less severe intellectual disability, but is more often associated with a severe and intractable myoclonic epilepsy

Increased Expression of the Large Conductance, Calcium-Activated K+ (BK) Channel in Adult-Onset Neuronal Ceroid Lipofuscinosis.

Cysteine string protein (CSPα) is a presynaptic J protein co-chaperone that opposes neurodegeneration. Mutations in CSPα (i.e., Leu115 to Arg substitution or deletion (Δ) of Leu116) cause adult neuronal ceroid lipofuscinosis (ANCL), a dominantly inherited neurodegenerative disease. We have previously demonstrated that CSPα limits the expression of large conductance, calcium-activated K+ (BK) channels in neurons, which may impact synaptic excitability and neurotransmission. Here we show by western blot analysis that expression of the pore-forming BKα subunit is elevated ~2.5 fold in the post-mortem cortex of a 36-year-old patient with the Leu116∆ CSPα mutation. Moreover, we find that the increase in BKα subunit level is selective for ANCL and not a general feature of neurodegenerative conditions. While reduced levels of CSPα are found in some postmortem cortex specimens from Alzheimer's disease patients, we find no concomitant increase in BKα subunit expression in Alzheimer's specimens. Both CSPα monomer and oligomer expression are reduced in synaptosomes prepared from ANCL cortex compared with control. In a cultured neuronal cell model, CSPα oligomers are short lived. The results of this study indicate that the Leu116∆ mutation leads to elevated BKα subunit levels in human cortex and extend our initial work in rodent models demonstrating the modulation of BKα subunit levels by the same CSPα mutation. While the precise sequence of pathogenic events still remains to be elucidated, our findings suggest that dysregulation of BK channels may contribute to neurodegeneration in ANCL

Efficient Delivery of <i>FMR1</i> across the Blood Brain Barrier Using AAVphp Construct in Adult <i>FMR1</i> KO Mice Suggests the Feasibility of Gene Therapy for Fragile X Syndrome

Background Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism. Gene therapy may offer an efficient method to ameliorate the symptoms of this disorder. Methods An AAVphp.eb-hSyn-mFMR1IOS7 vector and an empty control were injected into the tail vein of adult Fmr1 knockout (KO) mice and wildtype (WT) controls. The KO mice were injected with 2 × 1013 vg/kg of the construct. The control KO and WT mice were injected with an empty vector. Four weeks following treatment, the animals underwent a battery of tests: open field, marble burying, rotarod, and fear conditioning. The mouse brains were studied for levels of the Fmr1 product FMRP. Results: No significant levels of FMRP were found outside the CNS in the treated animals. The gene delivery was highly efficient, and it exceeded the control FMRP levels in all tested brain regions. There was also improved performance in the rotarod test and partial improvements in the other tests in the treated KO animals. Conclusion: These experiments demonstrate efficient, brain-specific delivery of Fmr1 via peripheral administration in adult mice. The gene delivery led to partial alleviation of the Fmr1 KO phenotypical behaviors. FMRP oversupply may explain why not all behaviors were significantly affected. Since AAV.php vectors are less efficient in humans than in the mice used in the current experiment, studies to determine the optimal dose using human-suitable vectors will be necessary to further demonstrate feasibility

BK channel co-immunoprecipitates with CSPα but not CSPα_HPD-AAA.

<p><b>(A)</b> CAD cells were transiently transfected with 1.0 μg cDNA encoding either CSPα_L115R, CSPα_L116Δ or CSPα_HPD-AAA in the presence and absence of 0.75 μg cDNA encoding myc tagged wild type CSPα and lysed 48 hours post-transfection. Western analysis and quantification of BK channel is shown; *p<0.05. Detection of β-actin on the same blot was used to verify equal loading between the various lanes. <b>(B)</b> CAD cells were transiently co-transfected with 1 μg BK channel and 0.75 μg myc-tagged CSPα, 0.75 μg myc-tagged CSPα_HPD-AAA and 0.75 μg pCMV (negative control). 0.7 mg of soluble cell lysate was subjected to immunoprecipitations with anti-myc monoclonal followed by Western blot analysis with anti-BK channel polyclonal and anti-myc monoclonal. The 55 kDa and 26kDa represent the heavy and light chain of the monoclonal myc-tag antibody. The right panel shows total cellular protein (input). Data are representative of three experiments.</p

BKα channel expression is elevated in ANCL.

<p>Western analysis of BKα channel, CSPα, and Hsc70 detected in 20μg of crude synaptosome fraction prepared from <u>human cortex</u> Control (34 yrs) and ANCL (L 116 Deletion; 36 yrs) as indicated. Detection of β-actin on the same blot was used to verify equal loading between the various lanes.</p

CSPα expression is lower in ANCL and some AD patients.

<p><b>(A)</b>Western analysis of CSPα, Dynamin 1, SNAP25, Hsc70 and β-actin detected in synaptosome fractions prepared from <u>human cortex</u> as indicated. For the 10 human samples the CSPα values were 671000, 459000, 583000, 530000, 684000, 690000, 351000, 432000, 397000, 342000. SNAP25 values were 2540000, 1640000, 2880000, 3040000, 3210000, 2530000, 2460000, 2050000, 2430000, 2140000, dynamin values were 3290000, 2160000, 3060000, 2580000, 3410000, 3500000, 3010000, 3240000, 2530000, 2300000 (B) Immunoblot showing CSPα monomer expression (left panel) and longer exposure showing high molecular weight CSPα oligomers (right panel) (C) mRNA levels for the indicated proteins (fold change compared to control brain tissue).</p