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Biomedical subjects

Nicole Philip

Publications and source records attributed to Nicole Philip.

At least 19 recordsLinked to original sources
PubMed2007

Truncation of NHEJ1 in a patient with polymicrogyria.

Polymicrogyria (PMG) is a common malformation of the human cerebral cortex for which both acquired and genetic causes are known. Although genetic heterogeneity is documented, only one gene is currently known to cause isolated PMG. To clone new genes involved in this type of cerebral malformation, we studied a fetus presenting a defect of cortical organization consisting of a polymicrogyric cortex and neuronal heterotopia within the white matter. Karyotype analysis revealed that the fetus was carrier of a balanced, de novo, chromosomal translocation t(2;7)(q35;p22). Cloning and sequencing of the two translocation breakpoints reveals that the chromosomal rearrangement disrupts the coding region of a single gene, called NHEJ1, Cernunnos, or XLF, in 2q35. The NHEJ1 gene was recently identified as being responsible for autosomal recessive immunodeficiency with microcephaly. Using quantitative PCR experiments, we show that a truncated transcript is expressed in the polymicrogyric patient cells, suggesting a potential dominant negative effect possibly leading to a different phenotype. We performed in situ hybridization on human embryos and showed that the NHEJ1 transcript is preferentially expressed in the telencephalic ventricular and subventricular zones, consistent with the phenotype of the affected individual. In the human adult central nervous system (CNS), NHEJ1 is mainly expressed in the cerebral cortex and in the cerebellum. The association of PMG with the disruption of its transcript suggests that, in addition to its recently uncovered function in the immune system, the NHEJ1 protein may also play a role during development of the human cerebral cortex.

Animals↗
PubMed2006

Involvement of hyperprolinemia in cognitive and psychiatric features of the 22q11 deletion syndrome.

Microdeletions of the 22q11 region, responsible for the velo-cardio-facial syndrome (VCFS), are associated with an increased risk for psychosis and mental retardation. Recently, it has been shown in a hyperprolinemic mouse model that an interaction between two genes localized in the hemideleted region, proline dehydrogenase (PRODH) and catechol-o-methyl-transferase (COMT), could be involved in this phenotype. Here, we further characterize in eight children the molecular basis of type I hyperprolinemia (HPI), a recessive disorder resulting from reduced activity of proline dehydrogenase (POX). We show that these patients present with mental retardation, epilepsy and, in some cases, psychiatric features. We next report that, among 92 adult or adolescent VCFS subjects, a subset of patients with severe hyperprolinemia has a phenotype distinguishable from that of other VCFS patients and reminiscent of HPI. Forward stepwise multiple regression analysis selected hyperprolinemia, psychosis and COMT genotype as independent variables influencing IQ in the whole VCFS sample. An inverse correlation between plasma proline level and IQ was found. In addition, as predicted from the mouse model, hyperprolinemic VCFS subjects bearing the Met-COMT low activity allele are at risk for psychosis (OR = 2.8, 95% CI = 1.04-7.4). Finally, from the extensive analysis of the PRODH gene coding sequence variations, it is predicted that POX residual activity in the 0-30% range results into HPI, whereas residual activity in the 30-50% range is associated either with normal plasma proline levels or with mild-to-moderate hyperprolinemia.

Adolescent↗
PubMed2006

Behavioral and temperamental features of children with Costello syndrome.

Costello syndrome (CS) is a rare genetic condition due to germline mutations in HRAS proto-oncogene and characterized by increased birth weight, postnatal growth retardation, distinctive facial appearance, typical medical problems (including feeding problems in the neonatal period), cutaneous anomalies, and developmental delay. Outgoing personality has often been noted in case reports, but few studies have focused specifically on the behavioral aspects of CS. A preliminary survey described irritability in younger patients with improvement between age 2 and 4, but a standardized psychometric tool was not used. A second study using the Child Behavior Checklist (CBCL) showed relatively high (albeit subclinical) levels of internalizing problems. These descriptive investigations lacked a control group. We describe a comparative survey to evaluate the behavioral and temperamental features of children with CS. We conducted a cross-sectional assessment using the CBCL and the Emotionality, Activity, Shyness, Sociability (EAS) temperament questionnaire to evaluate behavior and temperament in 11 CS children (2 years 5 months to 9 years) comparing them to 33 gender- and age-matched children without disability. The results suggest that the high levels of internalizing problems found before age 4 in CS patients might decrease with age. They also point to possible "hyperemotionality." Further studies using a larger sample size and IQ-matched control groups are needed to more accurately characterize individuals with this rare syndrome.

Abnormalities, Multiple↗
PubMed2006

Adams-Oliver syndrome associated with cutis marmorata telangiectatica congenita and congenital cataract: a case report.

A female infant presented with Adams-Oliver syndrome (AOS), intrauterine growth retardation, severe cutis marmorata telangiectatica congenita, bilateral congenital cataract, and periventricular lesions. The here-reported association of bilateral congenital cataract with AOS is original. Adams-Oliver syndrome is a genetic defect that causes a vasculopathy and leads to a variety of phenotypes. This observation further supports the current understanding of the physiopathology of AOS.

Abnormalities, Multiple↗
PubMed2005

Delineation of the clinical phenotype associated with OPHN1 mutations based on the clinical and neuropsychological evaluation of three families.

Recent reports have demonstrated that mutations in the OPHN1 gene were responsible for a syndromic rather than non-specific mental retardation. Abnormalities of the posterior fossa with cerebellar hypoplasia have been demonstrated in all male patients reported to date. We report here a new family with X-linked mental retardation due to mutation in OPHN1 and present unpublished data about two families previously reported, concerning the facial and psychological phenotype of affected males and carrier females. Our study confirms that cerebellar hypoplasia is a hallmark of this syndrome. In addition, affected males display facial similarities that can help the diagnosis. Most carrier females have mild mental retardation and subtle facial changes.

Cytoskeletal Proteins↗
PubMed2005

Identification of a new gene mutated in Fraser syndrome and mouse myelencephalic blebs.

Fraser syndrome is a recessive, multisystem disorder presenting with cryptophthalmos, syndactyly and renal defects and associated with loss-of-function mutations of the extracellular matrix protein FRAS1. Fras1 mutant mice have a blebbed phenotype characterized by intrauterine epithelial fragility generating serous and, later, hemorrhagic blisters. The myelencephalic blebs (my) strain has a similar phenotype. We mapped my to Frem2, a gene related to Fras1 and Frem1, and showed that a Frem2 gene-trap mutation was allelic to my. Expression of Frem2 in adult kidneys correlated with cyst formation in my homozygotes, indicating that the gene is required for maintaining the differentiated state of renal epithelia. Two individuals with Fraser syndrome were homozygous with respect to the same missense mutation of FREM2, confirming genetic heterogeneity. This is the only missense mutation reported in any blebbing mutant or individual with Fraser syndrome, suggesting that calcium binding in the CALXbeta-cadherin motif is important for normal functioning of FREM2.

Animals↗
PubMed2005

Further delineation of Kabuki syndrome in 48 well-defined new individuals.

Kabuki syndrome is a multiple congenital anomaly/mental retardation syndrome. This study of Kabuki syndrome had two objectives. The first was to further describe the syndrome features. In order to do so, clinical geneticists were asked to submit cases-providing clinical photographs and completing a phenotype questionnaire for individuals in whom they felt the diagnosis of Kabuki syndrome was secure. All submitted cases were reviewed by four diagnosticians familiar with Kabuki syndrome. The diagnosis was agreed upon in 48 previously unpublished individuals. Our data on these 48 individuals show that Kabuki syndrome variably affects the development and function of many organ systems. The second objective of the study was to explore possible etiological clues found in our data and from review of the literature. We discuss advanced paternal age, cytogenetic abnormalities, and familial cases, and explore syndromes with potentially informative overlapping features. We find support for a genetic etiology, with a probable autosomal dominant mode of inheritance, and speculate that there is involvement of the interferon regulatory factor 6 (IRF6) gene pathway. Very recently, a microduplication of 8p has been described in multiple affected individuals, the proportion of individuals with the duplication is yet to be determined.

Abnormalities, Multiple↗
PubMed2004

Macrocephaly-cutis marmorata telangiectatica congenita: seven cases including two with unusual cerebral manifestations.

Macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC) is a recently described multiple congenital anomaly/mental retardation (MCA/MR) syndrome of unknown cause. This condition is easily recognizable at birth in children with macrocephaly, cutis marmorata, face and/or body segmental overgrowth, toe syndactyly, midface capillary malformation, and hemimegalencephaly. Cutis marmorata may be absent in some cases. Most patients are developmentally delayed. We describe seven new patients, including two with unusual cerebral manifestations and severe outcome. One of two had a complex congenital heart defect (CHD) and died in the neonatal period. Brain magnetic resonance imaging (MRI) showed generalized cortical dysplasia. The other patient had a stroke episode at age 14 years. Cerebral arteriography showed an abnormal vascular pattern. These findings are consistent with the fact that M-CMTC is a generalized vasculopathy.

Abnormalities, Multiple↗
PubMed2004

Germline mutations of the paired-like homeobox 2B (PHOX2B) gene in neuroblastoma.

Neuroblastoma (NB) is a frequent pediatric tumor for which recurrent somatic rearrangements are known. Germline mutations of predisposing gene(s) are suspected on the basis of rare familial cases and the association of NB with other genetically determined congenital malformations of neural crest-derived cells--namely, Hirschsprung disease (HSCR) and/or congenital central hypoventilation syndrome (CCHS). We recently identified the paired-like homeobox 2B (PHOX2B) gene as the major disease-causing gene in isolated and syndromic CCHS, which prompted us to regard it as a candidate gene in NB. Here, we report on germline mutations of PHOX2B in both a familial case of NB and a patient with the HSCR-NB association. PHOX2B, therefore, stands as the first gene for which germline mutations predispose to NB.

Base Sequence↗
PubMed2003

MCA/MR syndrome with hypocholesterolemia related to familial dominant hypobetalipoproteinemia.

Recent reports have emphasized the role of cholesterol in vertebrate embryonic development. The RSH or so-called Smith-Lemli-Opitz syndrome (SLOS) was the first multiple congenital anomalies/mental retardation syndrome related to a cholesterol synthesis disturbance. Familial hypobetalipoproteinemia is a well-known dominantly inherited entity in which affected individuals usually are free of symptoms. We report on the unusual association of a malformation syndrome with mental retardation resembling SLOS and profound hypocholesterolemia related to familial hypobetalipoproteinemia. We discuss the possible causal relationship between the two conditions and the current understanding of the role of cholesterol in normal embryogenesis.

Cholesterol↗
PubMed2003

Screening for genetic disorders.

INTRODUCTION: Cerebral malformations can be genetically determined and/or part of complex syndromes. When the defect is detected during pregnancy, it important to rule out an associated genetic condition. Family history and detailed examination of fetal anatomy are needed. DISCUSSION: Intrauterine growth retardation, as well as limb abnormalities (especially polydactyly) are strong indicators of a genetic condition in the context of a fetal cerebral malformation. A standard chromosomal analysis is needed in all cases. Fluorescent in situ hybridization (FISH) techniques using locus-specific probes that permit the detection of subtle chromosomal rearrangements and metabolic analyses may be indicated when a specific condition is suspected. As for molecular analyses, they have so far been mainly applicable to pregnancies at risk of a known disorder because of family history. The diagnosis consists of determining whether the fetus has inherited the causative mutation identified in the index case. When termination of pregnancy is elicited, a careful prenatal and postnatal examination is needed in order to give accurate genetic counseling for further pregnancies. Storage of fetal material allowing further molecular analyses is strongly recommended.

Cells, Cultured↗
PubMed2003

Novel mutations in the TCIRG1 gene encoding the a3 subunit of the vacuolar proton pump in patients affected by infantile malignant osteopetrosis.

Fifty percent of the infantile malignant osteopetrosis (IMO) cases reported in the literature present mutations in the TCIRG1 gene encoding the 116-kDa osteoclast specific subunit of the vacuolar proton ATPase (ATP6I). In this study, we identified four novel mutations in a series of six IMO patients. All of these mutations correspond to single nucleotide changes and affect splice acceptor or donor sites, resulting in aberrant transcription products. We report also a missense mutation, G405R, previously described in several Costa Rican patients. This independent finding suggests that the highly conserved residue at amino acid 405 plays a critical role in the a3 subunit function. Finally, the results of this study were used to provide a prenatal diagnosis to one of the families.

Chromosomes, Human, Pair 11↗
PubMed2003

Fraser syndrome and mouse blebbed phenotype caused by mutations in FRAS1/Fras1 encoding a putative extracellular matrix protein.

Fraser syndrome (OMIM 219000) is a multisystem malformation usually comprising cryptophthalmos, syndactyly and renal defects. Here we report autozygosity mapping and show that the locus FS1 at chromosome 4q21 is associated with Fraser syndrome, although the condition is genetically heterogeneous. Mutation analysis identified five frameshift mutations in FRAS1, which encodes one member of a family of novel proteins related to an extracellular matrix (ECM) blastocoelar protein found in sea urchin. The FRAS1 protein contains a series of N-terminal cysteine-rich repeat motifs previously implicated in BMP metabolism, suggesting that it has a role in both structure and signal propagation in the ECM. It has been speculated that Fraser syndrome is a human equivalent of the blebbed phenotype in the mouse, which has been associated with mutations in at least five loci including bl. As mapping data were consistent with homology of FRAS1 and bl, we screened DNA from bl/bl mice and identified a premature termination of mouse Fras1. Thus, the bl mouse is a model for Fraser syndrome in humans, a disorder caused by disrupted epithelial integrity in utero.

Animals↗
PubMed2002

Prenatal diagnosis of Pierre-Robin sequence as part of Stickler syndrome.

Stickler syndrome or hereditary progressive arthro-ophthalmopathy, is an autosomal dominant condition characterized by ocular manifestations, arthritic changes, orofacial features and deafness, in variable degrees.We report the first case of prenatal diagnosis of Stickler syndrome in a child with a Pierre-Robin sequence (PRS) causing a polyhydramnios. When isolated polyhydramnios is not explained by immunological, metabolic or infectious causes, swallowing difficulty due to PRS must be considered. As PRS is aetiologically heterogeneous, the prognosis depends on the cause. Genetic investigations and familial history must be taken into account. Here, in a context of familial Stickler syndrome, making the prenatal diagnosis of PRS as part of Stickler syndrome allowed us to reassure the parents and to anticipate airway trouble at the child's birth.

Abnormalities, Multiple↗
PubMed2002

Prenatal detection of the 17p11.2 duplication in Charcot-Marie-Tooth disease type 1A: necessity of a multidisciplinary approach for heterogeneous disorders.

Charcot-Marie-Tooth (CMT) disease is a typical example of a clinically and genetically heterogeneous disorder and, in most cases, is dominantly inherited and caused by a 1.5 megabase duplication on chromosome 17p11.2 containing the PMP22 gene. This is a non-lethal disease with a wide spectrum of severity, from asymptomatism to severe motor and sensory disability. Unpredictable degree of disability is usually the reason why prenatal diagnosis is required and must be addressed. Molecular procedures such as the use of polymorphic non microsatellite STRs, allowing very fast and reliable results even when requiring a gene dosage interpretation are now available and have been recently validated in post-natal diagnosis. Our results indicate that this approach is also the best-adapted method in case of prenatal diagnosis. Nevertheless, ethical considerations raised by prenatal diagnosis in CMT and more generally in non-lethal disorders remain to be actively considered. Here, we present our experience in genetic counselling, and address the psychological issues for 7 CMT at risk pregnancies. In five cases, a CMT1A duplication was evidenced; pregnancy was terminated in four of these cases and the parents from one affected foetus decided to pursue the pregnancy.

Charcot-Marie-Tooth Disease↗