Parisi et al. (2004) reported 2 sibs with a relatively mild form of Joubert syndrome. One sib had mild gross motor delay, mild cognitive impairment, hypotonia, c...
Parisi et al. (2004) reported 2 sibs with a relatively mild form of Joubert syndrome. One sib had mild gross motor delay, mild cognitive impairment, hypotonia, congenital head tilt, abnormal eye movements consistent with oculomotor apraxia, and nephronophthisis diagnosed at age 10 years. MRI scan showed hypoplasia of the cerebellar vermis and the 'molar tooth sign.' Her sister had similar findings, but had normal cognitive function and was without renal involvement at age 8 years. Neither sib had retinal dystrophy or abnormal breathing patterns in infancy.
▼ Molecular Genetics
In 2 sibs with Joubert syndrome, Parisi et al. (2004) demonstrated homozygous deletion of the NPHP1 gene (607100.0005) identical to that which causes juvenile nephronophthisis (256100). The authors concluded that mutations in the NPHP1 gene are a rare cause of Joubert syndrome.
In 4 patients with Joubert syndrome from 3 nonconsanguineous families, Parisi et al. (2006) identified homozygosity for deletion of the NPHP1 gene. The molar tooth sign in these patients had a distinctive appearance, with elongated but not thickened superior cerebellar peduncles.