ABSTRACT
CAPZA2 encodes the α2 subunit of CAPZA, which is vital for actin polymerization and depolymerization in humans. However, understanding of diseases associated with CAPZA2 remains limited. To date, only three cases have been documented with neurodevelopmental abnormalities such as delayed motor development, speech delay, intellectual disability, hypotonia, and a history of seizures. In this study, we document a patient who exhibited seizures, mild intellectual disability, and impaired motor development yet did not demonstrate speech delay or hypotonia. The patient also suffered from recurrent instances of respiratory infections, gastrointestinal and allergic diseases. A novel de novo splicing variant c.219+1 G > A was detected in the CAPZA2 gene through whole-exome sequencing. This variant led to exon 4 skipping in mRNA splicing, confirmed by RT-PCR and Sanger sequencing. To our knowledge, this is the third study on human CAPZA2 defects, documenting the fourth unambiguously diagnosed case. Furthermore, this splicing mutation type is reported here for the first time. Our research offers additional support for the existence of a CAPZA2-related non-syndromic neurodevelopmental disorder. Our findings augment our understanding of the phenotypic range associated with CAPZA2 deficiency and enrich the knowledge of the mutational spectrum of the CAPZA2 gene.
Subject(s)
CapZ Actin Capping Protein , Developmental Disabilities , Epilepsy , Heterozygote , Muscle Hypotonia , Mutation , Child, Preschool , Female , Humans , Male , Developmental Disabilities/genetics , Developmental Disabilities/pathology , Epilepsy/genetics , Exome Sequencing , Intellectual Disability/genetics , Intellectual Disability/pathology , Muscle Hypotonia/genetics , Muscle Hypotonia/pathology , Phenotype , RNA Splicing/genetics , CapZ Actin Capping Protein/geneticsABSTRACT
Tubulin beta eight class VIII (TUBB8) is a subtype of ß-tubulin that only exists in primates. Mutations in the TUBB8 gene have been proven to cause oocyte maturation arrest. The aim of this study was to identify the new types of mutations in TUBB8. Six women (families) with oocyte maturation arrest and 100 healthy controls were recruited. The sequence of the TUBB8 gene was amplified and analyzed by Sanger sequencing, which revealed a de novo heterozygous variant c.292G > A (p.G98R) of TUBB8 in one affected individual. This TUBB8 variant was absent in the 100 fertile females and was predicted to be highly damaging to the function of the TUBB8 protein by SIFT and PolyPhen-2. This novel variant extends the spectrum of TUBB8 mutations and the presence of a TUBB8 mutation is being considered to be indicative of a poor prognosis for the success of assisted reproductive treatment.
