4 research outputs found
The broad phenotypic spectrum of PPP2R1A-related neurodevelopmental disorders correlates with the degree of biochemical dysfunction
Purpose: Neurodevelopmental disorders (NDD) caused by protein
phosphatase 2A (PP2A) dysfunction have mainly been associated
with de novo variants in PPP2R5D and PPP2CA, and more rarely in
PPP2R1A. Here, we aimed to better understand the latter by
characterizing 30 individuals with de novo and often recurrent
variants in this PP2A scaffolding Aα subunit.
Methods: Most cases were identified through routine clinical
diagnostics. Variants were biochemically characterized for phosphatase activity and interaction with other PP2A subunits.
Results: We describe 30 individuals with 16 different variants in
PPP2R1A, 21 of whom had variants not previously reported. The severity
of developmental delay ranged from mild learning problems to severe
intellectual disability (ID) with or without epilepsy. Common features
were language delay, hypotonia, and hypermobile joints. Macrocephaly
was only seen in individuals without B55α subunit-binding deficit, and
these patients had less severe ID and no seizures. Biochemically more
disruptive variants with impaired B55α but increased striatin binding
were associated with profound ID, epilepsy, corpus callosum hypoplasia,
and sometimes microcephaly.
Conclusion: We significantly expand the phenotypic spectrum of
PPP2R1A-related NDD, revealing a broader clinical presentation of the
patients and that the functional consequences of the variants are more
diverse than previously reported
The broad phenotypic spectrum of PPP2R1A-related neurodevelopmental disorders correlates with the degree of biochemical dysfunction
Purpose: Neurodevelopmental disorders (NDD) caused by protein phosphatase 2A (PP2A) dysfunction have mainly been associated with de novo variants in PPP2R5D and PPP2CA, and more rarely in PPP2R1A. Here, we aimed to better understand the latter by characterizing 30 individuals with de novo and often recurrent variants in this PP2A scaffolding Aα subunit. Methods: Most cases were identified through routine clinical diagnostics. Variants were biochemically characterized for phosphatase activity and interaction with other PP2A subunits. Results: We describe 30 individuals with 16 different variants in PPP2R1A, 21 of whom had variants not previously reported. The severity of developmental delay ranged from mild learning problems to severe intellectual disability (ID) with or without epilepsy. Common features were language delay, hypotonia, and hypermobile joints. Macrocephaly was only seen in individuals without B55α subunit-binding deficit, and these patients had less severe ID and no seizures. Biochemically more disruptive variants with impaired B55α but increased striatin binding were associated with profound ID, epilepsy, corpus callosum hypoplasia, and sometimes microcephaly. Conclusion: We significantly expand the phenotypic spectrum of PPP2R1A-related NDD, revealing a broader clinical presentation of the patients and that the functional consequences of the variants are more diverse than previously reported
Taxane benefit in breast cancer--a role for grade and chromosomal stability
Chromosomal instability, which is a characteristic of many human cancers, contributes to intratumour heterogeneity and has been functionally implicated in resistance to taxane therapy in tumour models. However, defining the status of tumour chromosomal instability in a given tumour to test this hypothesis remains challenging. Measurements of numerical and structural chromosomal heterogeneity demonstrate that histological grade correlates with chromosomal instability in oestrogen receptor (ER)-positive breast cancer. Using data on adjuvant taxane therapy in women with breast cancer, we propose that patients with low-grade ER-positive tumours, which are thought to be chromosomally stable, might derive unexpected benefit from taxane therapy. We discuss the implications of the relationships between tumour grade, chromosomal instability and intratumour heterogeneity, the development of high-throughput methods to define tumour chromosomal instability and the potential use of chromosomal instability to tailor therapy