Showing papers on "Neurocristopathy published in 2011"

Genotype-Phenotype Analysis of the Branchio-Oculo-Facial Syndrome

Abstract: Branchio-oculo-facial syndrome (BOFS; OMIM#113620) is a rare autosomal dominant craniofacial disorder with variable expression. Major features include cutaneous and ocular abnormalities, characteristic facies, renal, ectodermal, and temporal bone anomalies. Having determined that mutations involving TFAP2A result in BOFS, we studied a total of 30 families (41 affected individuals); 26/30 (87%) fulfilled our cardinal diagnostic criteria. The original family with the 3.2 Mb deletion including the TFAP2A gene remains the only BOFS family without the typical CL/P and the only family with a deletion. We have identified a hotspot region in the highly conserved exons 4 and 5 of TFAP2A that harbors missense mutations in 27/30 (90%) families. Several of these mutations are recurrent. Mosaicism was detected in one family. To date, genetic heterogeneity has not been observed. Although the cardinal criteria for BOFS have been based on the presence of each of the core defects, an affected family member or thymic remnant, we documented TFAP2A mutations in three (10%) probands in our series without a classic cervical cutaneous defect or ectopic thymus. Temporal bone anomalies were identified in 3/5 patients investigated. The occurrence of CL/P, premature graying, coloboma, heterochromia irides, and ectopic thymus, are evidence for BOFS as a neurocristopathy. Intrafamilial clinical variability can be marked. Although there does not appear to be mutation-specific genotype–phenotype correlations at this time, more patients need to be studied. Clinical testing for TFAP2A mutations is now available and will assist geneticists in confirming the typical cases or excluding the diagnosis in atypical cases. © 2010 Wiley-Liss, Inc.

Low amounts of PHOX2B expanded alleles in asymptomatic parents suggest unsuspected recurrence risk in congenital central hypoventilation syndrome

Abstract: Heterozygous trinucleotide in frame duplications, leading to expansions of variable lengths of a 20-alanine stretch (polyAla), is the most frequent PHOX2B variant associated with congenital central hypoventilation syndrome (CCHS), a rare neurocristopathy characterized by defective response of the autonomic nervous system to hypoxia and hypercapnia. Sequencing analysis has shown that the vast majority of polyAla expansions arise de novo; while in about 10% of cases, mutations are inherited by one parent who carries either constitutive or somatic mutations. To investigate transmission of PHOX2B mutant alleles from asymptomatic individuals, we have reassessed 44 parental pairs, previously resulted not to carry any mutation, by coupling amplification with FAM-tagged primers and capillary electrophoresis. Low levels of somatic mosaicism were shown in five parents previously undetected, thus increasing the inherited occurrence of the disease from 10% to 25% of the cases. Analysis of the technical detection limits has confirmed a power of resolution much higher for the "FAM" protocol than for the "sequencing" method. These observations are going to have relevant implications on how the carrier status of asymptomatic parents should be assessed and on successive genetic counseling to CCHS families.

Metabolic syndromes and neural crest development

Abstract: Aim of this study is to investigate for the possible connection between abnormal neural crest cell (NCC) development and NCC-derived abnormal facial and cerebral structures in 3 children with pyruvate-dehydrogenase (PDH) and in 10 cases with oxidative phosphorylation deficiency diagnosed from the Author by standard laboratory assays [i.e. 3 cases of Kearns-Sayre syndrome (KSS), 2 cases of Leigh syndrome, 1 case of KSS with De Toni-Debre-Fanconi and rachitis (Berio disease), 1 case of KSS with aortic insuffiency and sub-aortic septum hyperthophy, 3 cases of chronic progressive external ophthalmoplegia]. There patients presented with hyperlactacidemia, hyperpyruvicemia and facial abnormalities, similar to those observed in the fetal alcohol syndrome (a typical neurocristopathy) due to PDH deficiency, down-regulating NCC genes. The Author hypothesizes that the metabolic defect of scarce energy production is responsible of abnormal NCC proliferation/migration and consequent facial abnormalities.

[Study of polymorphisms associated to Hirschsprung's disease].

Abstract: Hirschsprung's disease (HSCR) is a developmental disorder characterised by the absence of the enteric ganglia along the intestine. Is regarded as the consequence of the premature arrest of the migration of neural crest cells in the hindgut during the embryonic development to form the enteric nervous system (ENS). Is considered, therefore, a neurocristopathy. The development of surgical approaches has importantly decreased mortality and morbility of Hirschsprung's patients, which has allowed the emergence of genetic studies of patients and their families. Although the genetic cause of the disease is still unknown, the RET oncogene is the main involved. Alterations in this gene have been found in HSCR patients, so many authors suggest that certain polymorphisms (SNPs) in this gene could be responsible of genetic predisposition to have the disease. Our work has consisted in the genetic analysis of the RET gene in HSCR patients using direct sequencing and genotyping with TaqMan probes. Our results show that some alleles of the polymorphisms p.Leu769Leu (c.2307T>G, Exon 13) p.Gly691Ser (c.2071G>A, Exon 11) and p.Ser904Ser (c.2712C>G, Exon 15) are associated to the disease since there are significant differences from the healthy population.