Joubert Syndrome 7

Alternative Names

  • JBTS7

Associated Genes

RPGRIP1-Like
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

OMIM Number

611560

Mode of Inheritance

Autosomal recessive

Gene Map Locus

16q12.2

Description

Joubert syndrome is a phenotypically heterogeneous ciliopathy classically defined by the presence of a molar tooth sign on brain imaging studies caused by cerebellar vermian hypoplasia and brainstem abnormalities.  Symptoms of the subtype JBTS7 include developmental delay, intellectual disability, ataxia, hypotonia and breathing dysregulation.  Ocular anomalies may include oculomotor apraxia, nystagmus, ptosis and strabismus.  Skeletal defects may include postaxial polydactyly of both hands and feet as well as scoliosis.  Renal defects include nephronophthisis, increased echogenicity and renal cysts, with most patients suffering from end stage renal disease by the first or second decade of life.

JBTS7 follows an autosomal recessive pattern of inheritance and is caused by mutations in the RPGRIP1L gene.  The gene encodes a ciliary protein responsible for negatively regulating signaling through the G-protein coupled thromboxane A2 receptor.  Both homozygous and compound heterozygous mutations in RPGRIP1L are associated with JBTS7.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
611560.1Saudi ArabiaMaleYes Global developmental delay; Generalized ...NM_015272.5:c.1649A>GHomozygousAutosomal, RecessiveAlazami et al. 2012 Has 2 other similarl...
611560.G.1Saudi ArabiaYesYes Global developmental delay; Polyhydramni...NM_015272.5:c.1649A>GHomozygousAutosomal, RecessiveMaddirevula et al. 2018 Three related patien...

Other Reports

Saudi Arabia

Al-Hamed et al. (2016) studied a cohort of 44 Saudi families affected by antenatal cystic kidney disease.  In one consanguineous family, the antenatal ultrasound examination found cystic kidneys along with oligohydramnios/anhydramnios.  The proband had three other affected siblings and the case resulted in fetal death.  Genetic screening of 90 renal genes found the fetus to be compound heterozygous for known mutations in the RPGRIP1L gene (c.640G>A p.V214I; C.685G>A, p.A229T).  The first mutation was predicted to be pathogenic while the second had been shown to compromise the interaction of RPGRIP1L with RPGR. 

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