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Phenotypic spectrum and prevalence of INPP5E mutations in Joubert syndrome and related disorders

Lorena Travaglini1, Francesco Brancati, Jennifer Silhavy

  • 11] IRCCS Casa Sollievo della Sofferenza, Mendel Laboratory San Giovanni Rotondo, San Giovanni Rotondo, Italy [2] Unit of Molecular Medicine for Neuromuscular and Neurodegenerative Diseases, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.

European Journal of Human Genetics : EJHG
|February 7, 2013
PubMed

Insights

Mutations in the INPP5E gene cause Joubert syndrome, a rare genetic disorder. This study found INPP5E mutations in 2.7% of Joubert syndrome patients, often presenting with eye abnormalities.

Area of Science:

  • Genetics
  • Developmental Biology
  • Medical Genetics

Background:

  • Joubert syndrome and related disorders (JSRD) are ciliopathies characterized by a distinctive 'molar tooth sign' midbrain-hindbrain malformation.
  • Genetic heterogeneity is high, with 19 causative genes identified, all encoding primary ciliary proteins.
  • Clinical and genetic overlap exists with other ciliopathies, notably Meckel syndrome (MKS).

Purpose of the Study:

  • To investigate the phenotypic spectrum and prevalence of INPP5E mutations in Joubert syndrome and related disorders (JSRD) and Meckel syndrome (MKS).
  • To analyze INPP5E mutation frequency in a large cohort of JSRD patients and MKS fetuses.

Main Methods:

  • INPP5E mutation analysis was performed on 483 probands (408 JSRD patients, 75 MKS fetuses).
  • Clinical data from affected families were collected and analyzed.

Main Results:

  • Twelve distinct INPP5E mutations were identified in 17 JSRD probands from 11 families, yielding an overall mutation frequency of 2.7% in JSRD.
  • The most common phenotype was Joubert syndrome with ocular involvement (64%), including retinopathy and/or colobomas.
  • No INPP5E mutations were found in MKS fetuses, and kidney, liver, or skeletal involvement was absent in affected JSRD families.

Conclusions:

  • INPP5E is a significant causative gene for JSRD, particularly in cases with ocular anomalies.
  • INPP5E mutations do not appear to cause Meckel syndrome, suggesting locus specificity.
  • Further research into INPP5E's role in ciliopathies is warranted.

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