Deep intronic variant in MVK as a cause for mevalonic aciduria initially presenting as non-syndromic retinitis pigmentosa.
Clin Genet
; 102(6): 524-529, 2022 Dec.
Article
em En
| MEDLINE
| ID: mdl-35916082
ABSTRACT
Non-syndromic retinitis pigmentosa (NSRP) is a clinically and genetically heterogeneous group of disorders characterized by progressive degeneration of the rod and cone photoreceptors, often leading to blindness. The evolving association of syndromic genes to cause NSRP and the increasing role of intronic variants in explaining missing heritability in genetic disorders present challenges in establishing conclusive clinical and genetic diagnoses. This study sought to identify and validate the causative genetic variant(s) in a 13-year-old male initially diagnosed with NSRP. Genome sequencing identified a pathogenic missense variant in MVK [NM_000431.3c.803T>C (p.Ile268Thr)], in trans with a novel intronic variant predicted to create a new donor splice site (c.768+71C>A). Proband cDNA analysis confirmed the inclusion of the first 68 base pairs of intron 8 that resulted in a frameshift in MVK (r.768_769ins[768+1_768+68]) and significantly reduced the expression of reference transcript (17.6%). Patient re-phenotyping revealed ataxia, cerebellar atrophy, elevated urinary mevalonate and LTE4 , in keeping with mild mevalonic aciduria and associated syndromic retinitis pigmentosa. Leakage of reference transcript likely explains the milder phenotype observed in our patient. This is the first association of a deep intronic splice variant to cause MVK-related disorder. This report highlights the importance of variant validation and patient re-phenotyping in establishing accurate diagnosis in the era of genome sequencing.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retinose Pigmentar
/
Deficiência de Mevalonato Quinase
Tipo de estudo:
Prognostic_studies
Limite:
Humans
/
Male
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article