1. CHAMP1-related disorders: pathomechanisms triggered by different genomic alterations define distinct nosological categories
- Author
-
Amenta, Simona, Marangi, Giuseppe, Orteschi, D., Frangella, Silvia, Gurrieri, Fiorella, Paccagnella, E., Torella, A., Cappuccio, G., Musacchia, F., Mutarelli, Massimiano, Carrella, D., Vitiello, G., Parenti, Gian Paolo, Leuzzi, V., Selicorni, A., Maitz, S., Brunetti-Pierri, N., Banfi, S., Montomoli, M., Milani, Daniela, Romano, Maria Concetta, Tummolo, Aida Angela, De Brasi, D., Coppola, A., Santoro, C., Scala, M., Romano, Federica, Capra, V., Nigro, V., Zollino, Marcella, Amenta S., Marangi G. (ORCID:0000-0002-6898-8882), Frangella S., Gurrieri F. (ORCID:0000-0002-6775-5972), Mutarelli M., Parenti G., Milani D., Romano C., Tummolo A., Romano F., Zollino M. (ORCID:0000-0003-4871-9519), Amenta, Simona, Marangi, Giuseppe, Orteschi, D., Frangella, Silvia, Gurrieri, Fiorella, Paccagnella, E., Torella, A., Cappuccio, G., Musacchia, F., Mutarelli, Massimiano, Carrella, D., Vitiello, G., Parenti, Gian Paolo, Leuzzi, V., Selicorni, A., Maitz, S., Brunetti-Pierri, N., Banfi, S., Montomoli, M., Milani, Daniela, Romano, Maria Concetta, Tummolo, Aida Angela, De Brasi, D., Coppola, A., Santoro, C., Scala, M., Romano, Federica, Capra, V., Nigro, V., Zollino, Marcella, Amenta S., Marangi G. (ORCID:0000-0002-6898-8882), Frangella S., Gurrieri F. (ORCID:0000-0002-6775-5972), Mutarelli M., Parenti G., Milani D., Romano C., Tummolo A., Romano F., and Zollino M. (ORCID:0000-0003-4871-9519)
- Abstract
Loss-of-function variants in CHAMP1 were recently described as cause of a neurodevelopmental disorder characterized by intellectual disability (ID), autism, and distinctive facial characteristics. By exome sequencing (ES), we identified a truncating variant in CHAMP1, c.1858A > T (p.Lys620*), in a patient who exhibited a similar phenotype of severe ID and dysmorphisms. Whether haploinsufficiency or a dominant negative effect is the underlying pathomechanism in these cases is a question that still needs to be addressed. By array-CGH, we detected a 194 kb deletion in 13q34 encompassing CHAMP1, CDC16 and UPF3, in another patient who presented with borderline neurodevelopmental impairment and with no dysmorphisms. In a further patient suffering from early onset refractory seizures, we detected by ES a missense variant in CHAMP1, c.67 G > A (p.Gly23Ser). Genomic abnormalities were all de novo in our patients. We reviewed the clinical and the genetic data of patients reported in the literature with: loss-of-function variants in CHAMP1 (total 40); chromosome 13q34 deletions ranging from 1.1 to 4 Mb (total 7) and of the unique patient with a missense variant. We could infer that loss-of-function variants in CHAMP1 cause a homogeneous phenotype with severe ID, autism spectrum disorders (ASD) and highly distinctive facial characteristics through a dominant negative effect. CHAMP1 haploinsufficiency results in borderline ID with negligible consequences on the quality of life. Missense variants give rise to a severe epileptic encephalopathy through gain-of-function mechanism, most likely. We tentatively define for the first time distinct categories among the CHAMP1-related disorder on the basis of pathomechanisms.
- Published
- 2023