Biallelic mutations in RNF220 cause laminopathies featuring leukodystrophy, ataxia and deafness.

Sferra A, Fortugno P, Motta M, Aiello C, Petrini S, Ciolfi A, Cipressa F, Moroni I, Leuzzi V, Pieroni L, Marini F, Boespflug Tanguy O, Eymard-Pierre E, Danti FR, Compagnucci C, Zambruno G, Brusco A, Santorelli FM, Chiapparini L, Francalanci P, Loizzo AL, Tartaglia M, Cestra G, Bertini E.

Brain. 2021 Nov 29;144(10):3020-3035. doi: 10.1093/brain/awab185.

Abstract

Leukodystrophies are a heterogeneous group of rare inherited disorders that mostly involve the white matter of the CNS. These conditions are characterized by primary glial cell and myelin sheath pathology of variable aetiology, which causes secondary axonal degeneration, generally emerging with disease progression. Whole exome sequencing performed in five large consanguineous nuclear families allowed us to identify homozygosity for two recurrent missense variants affecting highly conserved residues of RNF220 as the causative event underlying a novel form of leukodystrophy with ataxia and sensorineural deafness. We report these two homozygous missense variants (p.R363Q and p.R365Q) in the ubiquitin E3 ligase RNF220 as the underlying cause of this novel form of leukodystrophy with ataxia and sensorineural deafness that includes fibrotic cardiomyopathy and hepatopathy as associated features in seven consanguineous families. Mass spectrometry analysis identified lamin B1 as the RNF220 binding protein and co-immunoprecipitation experiments demonstrated reduced binding of both RNF220 mutants to lamin B1. We demonstrate that RNF220 silencing in Drosophila melanogaster specifically affects proper localization of lamin Dm0, the fly lamin B1 orthologue, promotes its aggregation and causes a neurodegenerative phenotype, strongly supporting the functional link between RNF220 and lamin B1. Finally, we demonstrate that RNF220 plays a crucial role in the maintenance of nuclear morphology; mutations in primary skin fibroblasts determine nuclear abnormalities such as blebs, herniations and invaginations, which are typically observed in cells of patients affected by laminopathies. Overall, our data identify RNF220 as a gene implicated in leukodystrophy with ataxia and sensorineural deafness and document a critical role of RNF220 in the regulation of nuclear lamina. Our findings provide further evidence on the direct link between nuclear lamina dysfunction and neurodegeneration.

Keywords: fibrotic cardiomyopathy; hepatopathy; laminopathies; leukodystrophy; sensorineural-deafness.

Variants in the degron of AFF3 are associated with intellectual disability, mesomelic dysplasia, horseshoe kidney, and epileptic encephalopathy.

Voisin N, Schnur RE, Douzgou S, Hiatt SM, Rustad CF, Brown NJ, Earl DL, Keren B, Levchenko O, Geuer S, Verheyen S, Johnson D, Zarate YA, Hančárová M, Amor DJ, Bebin EM, Blatterer J, Brusco A, Cappuccio G, Charrow J, Chatron N, Cooper GM, Courtin T, Dadali E, Delafontaine J, Del Giudice E, Doco M, Douglas G, Eisenkölbl A, Funari T, Giannuzzi G, Gruber-Sedlmayr U, Guex N, Heron D, Holla ØL, Hurst ACE, Juusola J, Kronn D, Lavrov A, Lee C, Lorrain S, Merckoll E, Mikhaleva A, Norman J, Pradervand S, Prchalová D, Rhodes L, Sanders VR, Sedláček Z, Seebacher HA, Sellars EA, Sirchia F, Takenouchi T, Tanaka AJ, Taska-Tench H, Tønne E, Tveten K, Vitiello G, Vlčková M, Uehara T, Nava C, Yalcin B, Kosaki K, Donnai D, Mundlos S, Brunetti-Pierri N, Chung WK, Reymond A.

Am J Hum Genet. 2021 May 6;108(5):857-873. doi: 10.1016/j.ajhg.2021.04.001.

Abstract

The ALF transcription factor paralogs, AFF1, AFF2, AFF3, and AFF4, are components of the transcriptional super elongation complex that regulates expression of genes involved in neurogenesis and development. We describe an autosomal dominant disorder associated with de novo missense variants in the degron of AFF3, a nine amino acid sequence important for its binding to ubiquitin ligase, or with de novo deletions of this region. The sixteen affected individuals we identified, along with two previously reported individuals, present with a recognizable pattern of anomalies, which we named KINSSHIP syndrome (KI for horseshoe kidney, NS for Nievergelt/Savarirayan type of mesomelic dysplasia, S for seizures, H for hypertrichosis, I for intellectual disability, and P for pulmonary involvement), partially overlapping the AFF4-associated CHOPS syndrome. Whereas homozygous Aff3 knockout mice display skeletal anomalies, kidney defects, brain malformations, and neurological anomalies, knockin animals modeling one of the microdeletions and the most common of the missense variants identified in affected individuals presented with lower mesomelic limb deformities like KINSSHIP-affected individuals and early lethality, respectively. Overexpression of AFF3 in zebrafish resulted in body axis anomalies, providing some support for the pathological effect of increased amount of AFF3. The only partial phenotypic overlap of AFF3- and AFF4-associated syndromes and the previously published transcriptome analyses of ALF transcription factors suggest that these factors are not redundant and each contributes uniquely to proper development.

Keywords: AFF3; AFF4; horseshoe kidney; intellectual disability; mesomelic dysplasia.

Motor and cognitive outcomes of cerebello-spinal stimulation in neurodegenerative ataxia

Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Valentina Dell’Era, Abhishek Datta, Chris Thomas, Camilla Ferrari, Alessio Di Fonzo, Roberto Fancellu, Mario Grassi, Alfredo Brusco, Antonella Alberici, Barbara Borroni

Brain, Volume 144, Issue 8, August 2021, Pages 2310–2321, https://doi.org/10.1093/brain/awab157

Abstract

Cerebellar ataxias represent a heterogeneous group of disabling disorders characterized by motor and cognitive disturbances, for which no effective treatment is currently available. In this randomized, double-blind, sham-controlled trial, followed by an open-label phase, we investigated whether treatment with cerebello-spinal transcranial direct current stimulation (tDCS) could improve both motor and cognitive symptoms in patients with neurodegenerative ataxia at short and long-term. Sixty-one patients were randomized in two groups for the first controlled phase. At baseline (T0), Group 1 received placebo stimulation (sham tDCS) while Group 2 received anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks (T1), with a 12-week (T2) follow-up (randomized, double-blind, sham controlled phase). At the 12-week follow-up (T2), all patients (Group 1 and Group 2) received a second treatment of anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks, with a 14-week (T3), 24-week (T4), 36-week (T5) and 52-week follow-up (T6) (open-label phase). At each time point, a clinical, neuropsychological and neurophysiological evaluation was performed. Cerebellar-motor cortex connectivity was evaluated using transcranial magnetic stimulation. We observed a significant improvement in all motor scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale), in cognition (evaluated with the cerebellar cognitive affective syndrome scale), in quality-of-life scores, in motor cortex excitability and in cerebellar inhibition after real tDCS compared to sham stimulation and compared to baseline (T0), both at short and long-term. We observed an addon-effect after two repeated treatments with real tDCS compared to a single treatment with real tDCS. The improvement at motor and cognitive scores correlated with the restoration of cerebellar inhibition evaluated with transcranial magnetic stimulation. Cerebello-spinal tDCS represents a promising therapeutic approach for both motor and cognitive symptoms in patients with neurodegenerative ataxia, a still orphan disorder of any pharmacological intervention.

Motor and cognitive outcomes of cerebello-spinal stimulation in neurodegenerative ataxia

Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Valentina Dell’Era, Abhishek Datta, Chris Thomas, Camilla Ferrari, Alessio Di Fonzo, Roberto Fancellu, Mario Grassi, Alfredo Brusco, Antonella Alberici, Barbara Borroni

Brain, Volume 144, Issue 8, August 2021, Pages 2310–2321, https://doi.org/10.1093/brain/awab157

Abstract

Cerebellar ataxias represent a heterogeneous group of disabling disorders characterized by motor and cognitive disturbances, for which no effective treatment is currently available. In this randomized, double-blind, sham-controlled trial, followed by an open-label phase, we investigated whether treatment with cerebello-spinal transcranial direct current stimulation (tDCS) could improve both motor and cognitive symptoms in patients with neurodegenerative ataxia at short and long-term. Sixty-one patients were randomized in two groups for the first controlled phase. At baseline (T0), Group 1 received placebo stimulation (sham tDCS) while Group 2 received anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks (T1), with a 12-week (T2) follow-up (randomized, double-blind, sham controlled phase). At the 12-week follow-up (T2), all patients (Group 1 and Group 2) received a second treatment of anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks, with a 14-week (T3), 24-week (T4), 36-week (T5) and 52-week follow-up (T6) (open-label phase). At each time point, a clinical, neuropsychological and neurophysiological evaluation was performed. Cerebellar-motor cortex connectivity was evaluated using transcranial magnetic stimulation. We observed a significant improvement in all motor scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale), in cognition (evaluated with the cerebellar cognitive affective syndrome scale), in quality-of-life scores, in motor cortex excitability and in cerebellar inhibition after real tDCS compared to sham stimulation and compared to baseline (T0), both at short and long-term. We observed an addon-effect after two repeated treatments with real tDCS compared to a single treatment with real tDCS. The improvement at motor and cognitive scores correlated with the restoration of cerebellar inhibition evaluated with transcranial magnetic stimulation. Cerebello-spinal tDCS represents a promising therapeutic approach for both motor and cognitive symptoms in patients with neurodegenerative ataxia, a still orphan disorder of any pharmacological intervention.

Motor and cognitive outcomes of cerebello-spinal stimulation in neurodegenerative ataxia

Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Alberto Benussi, Valentina Cantoni, Marta Manes, Ilenia Libri, Valentina Dell’Era, Abhishek Datta, Chris Thomas, Camilla Ferrari, Alessio Di Fonzo, Roberto Fancellu, Mario Grassi, Alfredo Brusco, Antonella Alberici, Barbara Borroni

Brain, Volume 144, Issue 8, August 2021, Pages 2310–2321, https://doi.org/10.1093/brain/awab157

Abstract

Cerebellar ataxias represent a heterogeneous group of disabling disorders characterized by motor and cognitive disturbances, for which no effective treatment is currently available. In this randomized, double-blind, sham-controlled trial, followed by an open-label phase, we investigated whether treatment with cerebello-spinal transcranial direct current stimulation (tDCS) could improve both motor and cognitive symptoms in patients with neurodegenerative ataxia at short and long-term. Sixty-one patients were randomized in two groups for the first controlled phase. At baseline (T0), Group 1 received placebo stimulation (sham tDCS) while Group 2 received anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks (T1), with a 12-week (T2) follow-up (randomized, double-blind, sham controlled phase). At the 12-week follow-up (T2), all patients (Group 1 and Group 2) received a second treatment of anodal cerebellar tDCS and cathodal spinal tDCS (real tDCS) for 5 days/week for 2 weeks, with a 14-week (T3), 24-week (T4), 36-week (T5) and 52-week follow-up (T6) (open-label phase). At each time point, a clinical, neuropsychological and neurophysiological evaluation was performed. Cerebellar-motor cortex connectivity was evaluated using transcranial magnetic stimulation. We observed a significant improvement in all motor scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale), in cognition (evaluated with the cerebellar cognitive affective syndrome scale), in quality-of-life scores, in motor cortex excitability and in cerebellar inhibition after real tDCS compared to sham stimulation and compared to baseline (T0), both at short and long-term. We observed an addon-effect after two repeated treatments with real tDCS compared to a single treatment with real tDCS. The improvement at motor and cognitive scores correlated with the restoration of cerebellar inhibition evaluated with transcranial magnetic stimulation. Cerebello-spinal tDCS represents a promising therapeutic approach for both motor and cognitive symptoms in patients with neurodegenerative ataxia, a still orphan disorder of any pharmacological intervention.

Atypical microdeletion 22q11.2 in a patient with tetralogy of Fallot

Carli D, Moroni A, Eleonora DG, Zonta A, Montin D, Licciardi F, Aidala E, Bordese R, Carlo PN, Brusco A, Giovanni Battista F, Mussa A.Affiliations expand

J Genet. 2021;100:5.

Abstract

The 22q11.2 microdeletion syndrome (22q11.2 DGS) is characterized by an extreme intrafamilial and interfamilial variability. The main clinical features are congenital heart defects, palatal abnormalities, learning disability, facial dysmorphisms and immune deficiency. In 85-90% of cases, the 22q11.2 DGS is caused by a heterozygous ~3-Mb deletion, including the TBX1 gene, considered one of the major genes responsible for heart defects. Individuals with atypical deletions with at least one breakpoint outside low copy repeats have been reported. Our patient is a child presenting tetralogy of Fallot (TOF) with an atypical 22q11.2 deletion proximal to the critical DiGeorge region. The rearrangement was inherited from the healthy mother and spanned ~642-970 kb, encompassing DGCR6 and PRODH, two novel possible candidate genes for conotruncal heart defects.

Abstract