Buried in the middle but guilty: Intronic mutations in the TCIRG1 gene cause human autosomal recessive osteopetrosis

Eleonora Palagano, Harry C. Blair, Alessandra Pangrazio, Irina Tourkova, Dario Strina, Andrea Angius, Gianmauro Cuccuru, Manuela Oppo, Paolo Uva, Wim Van Hul, Eveline Boudin, Andrea Superti-Furga, Flavio Faletra, Agostino Nocerino, Matteo C. Ferrari, Guido Grappiolo, Marta Monari, Alessandro Montanelli, Paolo Vezzoni, Anna VillaCristina Sobacchi

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Autosomal recessive osteopetrosis (ARO) is a rare genetic bone disease with genotypic and phenotypic heterogeneity, sometimes translating into delayed diagnosis and treatment. In particular, cases of intermediate severity often constitute a diagnostic challenge and represent good candidates for exome sequencing. Here, we describe the tortuous path to identification of the molecular defect in two siblings, in which osteopetrosis diagnosed in early childhood followed a milder course, allowing them to reach the adult age in relatively good conditions with no specific therapy. No clearly pathogenic mutation was identified either with standard amplification and resequencing protocols or with exome sequencing analysis. While evaluating the possible impact of a 3'UTR variant on the TCIRG1 expression, we found a novel single nucleotide change buried in the middle of intron 15 of the TCIRG1 gene, about 150 nucleotides away from the closest canonical splice site. By sequencing a number of independent cDNA clones covering exons 14 to 17, we demonstrated that this mutation reduced splicing efficiency but did not completely abrogate the production of the normal transcript. Prompted by this finding, we sequenced the same genomic region in 33 patients from our unresolved ARO cohort and found three additional novel single nucleotide changes in a similar location and with a predicted disruptive effect on splicing, further confirmed in one of them at the transcript level. Overall, we identified an intronic region in TCIRG1 that seems to be particularly prone to splicing mutations, allowing the production of a small amount of protein sufficient to reduce the severity of the phenotype usually associated with TCIRG1 defects. On this basis, we would recommend including TCIRG1 not only in the molecular work-up of severe infantile osteopetrosis but also in intermediate cases and carefully evaluating the possible effects of intronic changes.

Original languageEnglish
Pages (from-to)1814-1821
Number of pages8
JournalJournal of Bone and Mineral Research
Volume30
Issue number10
DOIs
Publication statusPublished - Oct 1 2015

Fingerprint

Osteopetrosis
Exome
Mutation
Nucleotides
Genes
Inborn Genetic Diseases
Bone Diseases
Delayed Diagnosis
3' Untranslated Regions
Introns
Siblings
Exons
Complementary DNA
Clone Cells
Phenotype
Therapeutics
Proteins

Keywords

  • autosomal recessive osteopetrosis
  • exome
  • hypomorphic mutation
  • splicing defect
  • TCIRG1

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Endocrinology, Diabetes and Metabolism

Cite this

Buried in the middle but guilty : Intronic mutations in the TCIRG1 gene cause human autosomal recessive osteopetrosis. / Palagano, Eleonora; Blair, Harry C.; Pangrazio, Alessandra; Tourkova, Irina; Strina, Dario; Angius, Andrea; Cuccuru, Gianmauro; Oppo, Manuela; Uva, Paolo; Van Hul, Wim; Boudin, Eveline; Superti-Furga, Andrea; Faletra, Flavio; Nocerino, Agostino; Ferrari, Matteo C.; Grappiolo, Guido; Monari, Marta; Montanelli, Alessandro; Vezzoni, Paolo; Villa, Anna; Sobacchi, Cristina.

In: Journal of Bone and Mineral Research, Vol. 30, No. 10, 01.10.2015, p. 1814-1821.

Research output: Contribution to journalArticle

Palagano, E, Blair, HC, Pangrazio, A, Tourkova, I, Strina, D, Angius, A, Cuccuru, G, Oppo, M, Uva, P, Van Hul, W, Boudin, E, Superti-Furga, A, Faletra, F, Nocerino, A, Ferrari, MC, Grappiolo, G, Monari, M, Montanelli, A, Vezzoni, P, Villa, A & Sobacchi, C 2015, 'Buried in the middle but guilty: Intronic mutations in the TCIRG1 gene cause human autosomal recessive osteopetrosis', Journal of Bone and Mineral Research, vol. 30, no. 10, pp. 1814-1821. https://doi.org/10.1002/jbmr.2517
Palagano, Eleonora ; Blair, Harry C. ; Pangrazio, Alessandra ; Tourkova, Irina ; Strina, Dario ; Angius, Andrea ; Cuccuru, Gianmauro ; Oppo, Manuela ; Uva, Paolo ; Van Hul, Wim ; Boudin, Eveline ; Superti-Furga, Andrea ; Faletra, Flavio ; Nocerino, Agostino ; Ferrari, Matteo C. ; Grappiolo, Guido ; Monari, Marta ; Montanelli, Alessandro ; Vezzoni, Paolo ; Villa, Anna ; Sobacchi, Cristina. / Buried in the middle but guilty : Intronic mutations in the TCIRG1 gene cause human autosomal recessive osteopetrosis. In: Journal of Bone and Mineral Research. 2015 ; Vol. 30, No. 10. pp. 1814-1821.
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