Effect of BTD gene variants on in vitro biotinidase activity.
Mol Genet Metab
; 127(4): 361-367, 2019 08.
Article
en En
| MEDLINE
| ID: mdl-31337602
ABSTRACT
INTRODUCTION:
Biotinidase deficiency (BD), an autosomal recessive disease, is classified into profound (activity <10%) or partial BD (activity 10-30%). The most frequent variant in patients worldwide is c.1330Gâ¯>â¯C (p.Asp444His), which is associated with partial BD. In vivo studies indicate that this variant reduces the biotinidase activity by 50%. The objective of this study was to evaluate the in vitro effect of p.Asp444His and of five novel variants identified among Brazilian individuals showing low activity of biotinidase in serum.METHODS:
The variants c.119â¯Tâ¯>â¯C (p.Leu40Pro), c.479Gâ¯>â¯A (p.Cys160Tyr), c.664Gâ¯>â¯A (p.Asp222Asn), c.1330Gâ¯>â¯C (p.Asp444His), c.1337â¯Tâ¯>â¯C (p.Leu446Pro), c.1466Aâ¯>â¯G (p.Asn489Ser) and the wild type (wt) BTD gene were expressed in HEK 293 cells. Biotinidase activity was quantified by colorimetric method in cells homogenates and culture medium. The wtBTD activity was considered 100%.RESULTS:
The p.Leu40Pro, p.Cys160Tyr and p.Leu446Pro variants were associated to impaired biotinidase activity (activity in cells 33%, 14%, 0%, respectively; activity in medium 7%, 0.3%, 2%, respectively) and undetectable amount of protein in intra and extracellular space. The p.Asn489Ser variant had these effects restricted to the extracellular space (activity in medium 43%), and the p.Asp222Asn variant showed normal activity. The expression of p.Asp444His variant resulted in detectable protein and slightly reduced activity only in cells (activity in cells 46%; activity in medium 115%).CONCLUSION:
Our findings suggest that the p.Leu40Pro, p.Cys160Tyr and p.Leu446Pro variants are deleterious; the p.Asn489Ser is probably related to a mild biochemical phenotype; and p.Asp222Asn variant is probably not deleterious. The p.Asp444His variant seems to code for a protein with variable activity.Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Variación Genética
/
Deficiencia de Biotinidasa
/
Biotinidasa
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Mol Genet Metab
Asunto de la revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
METABOLISMO
Año:
2019
Tipo del documento:
Article
País de afiliación:
Brasil