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A homozygote variant in the tRNA splicing endonuclease subunit 54 causes pontocerebellar hypoplasia in a consanguineous Iranian family.

ABSTRACT: BACKGROUND:Homozygous loss-of-function mutations in TSEN54 (tRNA splicing endonuclease subunit 54; OMIM: 608755) cause different types of pontocerebellar hypoplasias (PCH) including PCH2, PCH4, and PCH5. The study aimed to determine the possible genetic factors contributing to PCH phenotypes in two affected male infants in an Iranian family. METHODS:We subjected two affected individuals in a consanguineous Iranian family. To systematically investigate the susceptible gene(s), whole-exome sequencing was performed on the proband and a novel identified variant was confirmed by Sanger sequencing. We also analyzed 26 relatives in three generations using PCR-restriction fragment length polymorphism (PCR-RFLP) followed and confirmed by Sanger sequencing. RESULTS:Physical and medical examinations confirmed PCH in the patients. Besides, the proband showed bilateral moderate sensorineural hearing loss and structural heart defects as the novel phenotypes. The molecular findings also verified that two affected individuals were homozygote for the novel synonymous variant, NM_207346.2: c.1170G>A; p.(Val390Val), in TSEN54. PCR-RFLP and Sanger sequencing elucidated that the parents and 16 relatives were heterozygote for the novel variant. CONCLUSION:We identified a novel synonymous variant, c.1170G>A, in TSEN54 associated with PCH in an Iranian family. Based on this study, we strongly suggest using "TSENopathies" to show the overlapped phenotypes among different types of PCH resulted from TSEN causative mutations.

SUBMITTER: Sepahvand A

PROVIDER: S-EPMC7549571 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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A homozygote variant in the tRNA splicing endonuclease subunit 54 causes pontocerebellar hypoplasia in a consanguineous Iranian family.

Sepahvand Afrooz A Razmara Ehsan E Bitarafan Fatemeh F Galehdari Mohammad M Tavasoli Ali Reza AR Almadani Navid N Garshasbi Masoud M

Molecular genetics & genomic medicine 20200722 10

<h4>Background</h4>Homozygous loss-of-function mutations in TSEN54 (tRNA splicing endonuclease subunit 54; OMIM: 608755) cause different types of pontocerebellar hypoplasias (PCH) including PCH2, PCH4, and PCH5. The study aimed to determine the possible genetic factors contributing to PCH phenotypes in two affected male infants in an Iranian family.<h4>Methods</h4>We subjected two affected individuals in a consanguineous Iranian family. To systematically investigate the susceptible gene(s), whol ...[more]

PMID: 32697043

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Project description:IntroductionPontocerebellar hypoplasia Type 2 (PCH2) is a rare autosomal recessive condition, defined on MRI by a small cerebellum and ventral pons. Clinical features are severe developmental delay, microcephaly and dyskinesia.Ninety percent carry a p.A307S mutation in the TSEN54-gene. Our aim was to describe the natural course including neurological and developmental features and other aspects of care in a homogeneous group of PCH2 patients all carrying the p.A307S mutation.Patients and methodsPatients were recruited via the German patients' organizations. Inclusion criteria were imaging findings of PCH2 and a p.A307S mutation. Data were collected using medical reports and patient questionnaires discussed in a standardized telephone interview.ResultsThirty-three patients were included. When considering survival until age 11 years, 53% of children had died Weight, length and head circumference, mostly in the normal range at birth, became abnormal, especially head circumference (-5.58 SD at age 5 yrs). Neurologic symptoms: Choreathetosis was present in 88% (62% with pyramidal signs), 12% had pure spasticity. Epileptic seizures were manifest in 82%, status epilepticus in 39%. Non-epileptic dystonic attacks occurred in 33%. General symptoms: feeding difficulties were recorded in 100%, sleep disorder in 96%, apneas in 67% and recurrent infections in 52%; gastroesophageal reflux disease was diagnosed in 73%, 67% got percutaneous endoscopic gastrostomy and 36% a Nissen-fundoplication. Neurodevelopmental data: All children made progress, but on a low level: such as fixing and following with the eyes was seen in 76%, attempting to grasp objects (76%), moderate head control (73%), social smile (70%), rolling from prone to supine (58%), and sitting without support (9%). Ten percent lost achieved abilities on follow-up. The presence of prenatal symptoms did not correlate with outcome.ConclusionPhenotype of this genetically homogeneous group of PCH2 children was severe with reduced survival, but compatible with some developmental progress. Our data support the hypothesis of an early onset degeneration which thereafter stabilizes.

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A homozygote variant in the tRNA splicing endonuclease subunit 54 causes pontocerebellar hypoplasia in a consanguineous Iranian family.

Publications

A homozygote variant in the tRNA splicing endonuclease subunit 54 causes pontocerebellar hypoplasia in a consanguineous Iranian family.

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