Hirschsprung's disease: a more generalised neuropathy?

Sox10 regulates ciliary neurotrophic factor gene expression in Schwann cells

Ciliary neurotrophic factor (Cntf) plays an essential role in postnatal maintenance of spinal motoneurons. Whereas the expression of this neurotrophic factor is low during embryonic development, it is highly up-regulated after birth in myelinating Schwann cells of rodents. To characterize the underlying transcriptional mechanisms, we have analyzed and compared the effects of various glial transcription factors. In contrast to Pit-1, Oct-1, Unc-86 homology region (POU) domain class 3, transcription factor 1 (Oct6/SCIP/Tst-1) and paired box gene 3 (Pax3), SRY-box-containing gene 10 (Sox10) induces Cntf expression in Schwann cells. Subsequent promoter analysis using luciferase reporter gene and EMSA identified the corresponding response elements within the Cntf promoter. Overexpression of Sox10 in primary sciatic nerve Schwann cells leads to a >100-fold up-regulation of Cntf protein, and suppression of Sox10 by RNA interference in the spontaneously immortalized Schwann cell line 32 reduces Cntf expression by >80%. Mice with heterozygous inactivation of the Sox10 gene show significantly reduced Cntf protein levels in sciatic nerves, indicating that Sox10 is necessary and sufficient for regulating Cntf expression in the peripheral nervous system.

Neurocristopathies presenting with neurologic abnormalities associated with Hirschsprung's disease

Neurocristopathies are a group of diverse disorders resulting from defective growth, differentiation, and migration of the neural crest cells. Hirschsprung's disease, namely aganglionic megacolon, is the consequence of defective migration of neural crest cells on to the colonic submucosa and is therefore considered a neurocristopathy. We report on four children in whom was diagnosed a neurocristopathy, associating Hirschsprung's disease with a wide spectrum of neurologic abnormalities. The patients included two children presenting the phenotypic features of the Goldberg-Shprintzen syndrome: distinct dysmorphic facial features, microcephaly, and mental retardation, along with agenesis of the corpus callosum and cortical malformations associated with intractable seizures in one child. The third newborn presented with the Haddad syndrome: short-segment Hirschsprung's disease associated with the congenital central hypoventilation syndrome requiring permanent artificial ventilation. In the fourth child, absence of the corpus callosum was associated with mild dysmorphic features, borderline cognitive abilities, and attention-deficit disorder. Therefore, awareness of a possible neurocristopathy associated with neurologic abnormalities should be taken into account in any patient newly diagnosed with Hirschsprung's disease to detect the abnormalities early and promptly manage them. A thorough neurologic examination and a developmental assessment, including magnetic resonance imaging of the brain and electroencephalography, should be performed for any child presenting with an aganglionic megacolon, especially those presenting with seizures, developmental delay, or even congenital hypoventilation.

Clinical features of a form of Hirschsprung's disease caused by a novel genetic abnormality

BACKGROUND/PURPOSE

The aim of this report is to describe the pattern of similarities among the patients, exemplifying a newly recognized form of Hirschsprung's disease (HSCR) caused by mutations of ZFHX1B encoding Smad interacting protein-1.

METHODS

Fluorescence in situ hybridization (FISH) using several cDNAs and RP11-BAC clones and mutation gene scanning using direct nucleotide sequencing analysis of polymerase chain reaction (PCR) were conducted. Personal records of the patients also were analyzed retrospectively to confirm the clinical features.

RESULTS

All the patients represented isolated cases without any familial tendency. Aganglionic segments were limited to the recto-sigmoid colon in 3 cases and the rectum in one. Chromosomal screening found normal karyotypes in all cases except one, in whom a translocation between chromosomes 2 and 13 was detected. In addition to HSCR, characteristic facial appearance (hypertelorism with strabismus and wide nasal bridge), microcephaly with epilepsy, and severe physical and mental disabilities were found in all the patients. FISH for the patient having the chromosomal abnormality showed that about a 5-Mb cytogenetic deletion flanked at the 2q22 translocation breakpoint. Among 3 genes mapping to this deleted region, 2 nonsense mutations and a 4-base pair deletion were detected in ZFHX1B.

CONCLUSIONS

The clinical features of the patients have surprising resemblance and constitute a wide spectrum of neurocristopathies. These findings suggest that the ZFHX1B may be a very important gene for normal embryonic neural crest development. These also indicate that the HSCR can be regarded as a congenital malformation with a background of a multigenetic neurocristopathy. It is of great interest that mutations were located at the same spot (exon 8) of ZFHX1B in 3 of 4 cases, probably accounting for the unique clinical features of this newly recognized form of HSCR.