P-03
Recessive TTN truncating mutation define a novel antenatal severe form of “CAP-myopathy” in absence of heart disease
Ana Fernández-MarmiesseI; M. Carmen Carrascosa-RomeroII; Iria RocaI; Sofia GouveiaI; Mª Luz Couce PicoI
IHospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
IINeuropediatric Unit, Complejo Universitario Hospitalario de Albacete, Albacete, Spain
Background: Arthrogryposis multiplex congenital (AMC) is defined as multiple congenital non-progressive joint contractures involving more than one area of the body. Amyoplasia, is the most common type of arthrogryposis, characterized by a generalized replacement of skeletal muscle by dense fibrous tissue and fat. “CAP myopathy” is a rare congenital myopathy characterized by cap structures consisting of disarranged thin filaments with enlarged Z discs, located at the periphery of the muscle fiber. Four genes have been associated (ACTA1, TPM2, TPM3 and NEB). To date TTN gene has never been associated with “CAP-myopathy”.
Methods and results: We report a newborn presenting with AMC, severe axial hypotonia, and muscular biopsy compatible with amyoplasia and “CAP-myopathy”. A novel homozygous truncating mutation (c.38661_38669del) in the PEVK segment of TTN gene was detected by targeted next generation sequencing assay.
Conclusion: We report for first time an association between TTN gene and “CAP-myopathy”, showing that mutations in this gene should be considered in all congenital myopathies even if cardiac involvement is absent. We show also the first described TTN mutation which leads to totally sarcomere disintegration and placed in an exon only transcribed in fetal period (isoform IC).
Keywords: Arthrogryposis multiplex congenital, amyoplasia, “CAP-myopathy”, targeted NGS, TTN-PEVK
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