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S Lyonnet

Publications and source records attributed to S Lyonnet.

At least 37 records · Page 2Linked to original sources
PubMed2003

Early prognostic factors for intellectual outcome in CHARGE syndrome.

CHARGE syndrome (coloboma, heart disease, atresia of the choanae, retarded growth and mental development, genital anomalies, and ear malformations and hearing loss) is a heterogeneous condition for which early prediction of intellectual outcome is important but difficult. The psychomotor milestones and intellectual outcome of a consecutive series of children with CHARGE syndrome who were observed by the same team from the neonatal period to the time of study were analyzed retrospectively. Twenty-one children (11 males and 10 females, aged from 5 to 12 years, mean 8 years 7 months, SD 2 years 5 months) were included. The influence of 19 early identifiable parameters that could be considered as deleterious for intellectual outcome was recorded. Generally, the main psychomotor milestones (0 to 4 years) were severely delayed, although intellectual outcome (at primary-school age) was satisfactory for half the children in this series. We show that extensive bilateral coloboma resulting in low vision, microcephaly, and brain malformation were the only three parameters that were predictive of poor intellectual outcome. Conversely, severe neonatal medical conditions, such as tracheotomy, conditions requiring long stays in hospital, or cardiac surgery were not predictive of poor intellectual outcome. Severe hearing loss was not found to be negatively correlated with intellectual outcome once coloboma had been taken into account.

Abnormalities, Multiple↗
PubMed2003

Frameshift mutation of the zinc finger homeo box 1 B gene in syndromic corpus callosum agenesis (Mowat-Wilson syndrome).

We report a girl who had Hirschsprung disease in association with distinct facial appearance, microcephaly, agenesis of the corpus callosum and mental retardation (Mowat-Wilson syndrome). Mutation analysis of the zinc finger homeo box 1 B (ZFHX1 B) gene revealed a de novo 7 bp deletion (TGGCCCC) at nucleotide 1773 (1773 delTGGCCCC) resulting in a frameshift and leading to a termination codon at amino acid residue 604 (604 X) in exon 8 C. The zinc finger homeo box 1 B (Smad interacting protein-1) is a transcription corepressor of Smad target genes with functions in the patterning of neural crest derived cells, CNS, and midline structures. Mutations in ZFHX1 B can lead to neurological disorders in addition to dysmorphic features, megacolon, and other malformations.

Abnormalities, Multiple↗
PubMed2003

Spectrum of NSD1 mutations in Sotos and Weaver syndromes.

Sotos syndrome is an overgrowth syndrome characterised by pre- and postnatal overgrowth, macrocephaly, advanced bone age, and typical facial features. Weaver syndrome is a closely related condition characterised by a distinctive craniofacial appearance, advanced carpal maturation, widened distal long bones, and camptodactyly. Haploinsufficiency of the NSD1 gene has recently been reported as the major cause of Sotos syndrome while point mutations accounted for a minority of cases. We looked for NSD1 deletions or mutations in 39 patients with childhood overgrowth. The series included typical Sotos patients (23/39), Sotos-like patients (lacking one major criteria, 10/39), and Weaver patients (6/39). We identified NSD1 deletions (6/33) and intragenic mutations (16/33) in Sotos syndrome patients. We also identified NSD1 intragenic mutations in 3/6 Weaver patients. We conclude therefore that NSD1 mutations account for most cases of Sotos syndrome and a significant number of Weaver syndrome cases in our series. Interestingly, mental retardation was consistently more severe in patients with NSD1 deletions. Macrocephaly and facial gestalt but not overgrowth and advanced bone age were consistently observed in Sotos syndrome patients. We suggest therefore considering macrocephaly and facial gestalt as mandatory criteria for the diagnosis of Sotos syndrome and overgrowth and advanced bone age as minor criteria.

Abnormalities, Multiple↗
PubMed2002

Clinical and genetic heterogeneity of Seckel syndrome.

Seckel syndrome is a rare autosomal recessive condition belonging to the group of osteodysplastic primordial "dwarfism" and characterized by the association of 1) severe pre- and postnatal growth retardation, 2) microcephaly with mental retardation, and 3) specific dysmorphic features. Recently, two disease loci have been mapped to chromosomes 3q22.1-q24 and 18p11.31-q11.2, respectively, by homozygosity mapping in consanguineous families. Here, we report on the exclusion of these loci in five consanguineous and one multiplex nonconsanguineous Seckel syndrome families and in two consanguineous families presenting type II osteodysplastic primordial dwarfism. These results support the view that Seckel syndrome is a clinically and genetically heterogeneous condition.

Abnormalities, Multiple↗
PubMed2002

Progressive bulbospinal amyotrophy in triple A syndrome with AAAS gene mutation.

Triple A (3A) syndrome, a rare autosomal recessive disorder, is characterized by adrenocorticotropic hormone-resistant adrenal insufficiency, achalasia of the cardia, alacrima, and variable autonomic and neurologic dysfunction. The gene responsible, AAAS, recently has been identified. We describe the neurologic phenotype of the first adult case of 3A syndrome presenting bulbospinal amyotrophy as the prominent sign in association with a homozygous nonsense mutation identified in the AAAS gene.

Adrenal Gland Diseases↗
PubMed2002

[Neurofibromatosis 1: recommendations for management].

Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have elaborated recommendations for the management of the disease. Bibliography was obtained through a Medline of articles from 1966 to 1999 for the terms neurofibromatosis, NF1, neurofibroma and from textbooks. A consensual document was written taking into account extracted data. An annual careful clinical examination is recommended except in cases with complications. Screening investigations are not recommended due to the rarity of complications, generally symptomatic and easily detected during the clinical follow-up. The only controversial exception might be magnetic resonance imaging for early detection of optic pathway gliomas in young children. A co-ordinated follow-up in specialised multidisciplinary centres, providing patients with a rational management, is recommended.

Adolescent↗
PubMed2002

A CGH study of 27 patients with CHARGE association.

CHARGE association is a non-random occurrence of congenital malformations including coloboma, heart disease, choanal atresia, retarded growth and/or retarded development, genital hypoplasia, ear anomalies and/or deafness. The cause of this association remains unknown. Various genetic mechanisms have been proposed, including a contiguous gene syndrome but, so far, no recurrent locus has been identified. To address this question, we decided to perform a comparative genomic hybridization (CGH) study on a cohort of 27 patients with CHARGE association and a normal standard karyotype. We found two chromosomal anomalies: a der(9)t(9;13) derived from a paternal translocation and a der(6)t(4;6) of unknown origin. This suggests that chromosome imbalances may well mimic CHARGE association. Therefore patients with CHARGE association must be carefully tested with classical and molecular cytogenetic techniques to detect a potential chromosome imbalance. It is expected that more stringent diagnostic criteria of CHARGE association could define a more homogeneous group of patients where a single genetic cause might be identified.

Abnormalities, Multiple↗
PubMed2002

Automated fluorescent genotyping detects 10% of cryptic subtelomeric rearrangements in idiopathic syndromic mental retardation.

Recent studies have shown that cryptic unbalanced subtelomeric rearrangements contribute to a significant proportion of idiopathic syndromic mental retardation cases. Using a fluorescent genotyping based strategy, we found a 10% rate of cryptic subtelomeric rearrangements in a large series of 150 probands with severe idiopathic syndromic mental retardation and normal RHG-GTG banded karyotype. Fourteen children were found to carry deletions or duplications of one or more chromosome telomeres and two children had uniparental disomy. This study clearly shows that fluorescent genotyping is a sensitive and cost effective method that not only detects cryptic subtelomeric rearrangements but also provides a unique opportunity to detect uniparental disomies. We suggest giving consideration to systematic examination of subtelomeric regions in the diagnostic work up of patients with unexplained syndromic mental retardation.

Child↗
PubMed2001

Survival of male patients with incontinentia pigmenti carrying a lethal mutation can be explained by somatic mosaicism or Klinefelter syndrome.

Incontinentia pigmenti (IP), or "Bloch-Sulzberger syndrome," is an X-linked dominant disorder characterized by abnormalities of skin, teeth, hair, and eyes; skewed X-inactivation; and recurrent miscarriages of male fetuses. IP results from mutations in the gene for NF-kappaB essential modulator (NEMO), with deletion of exons 4-10 of NEMO accounting for >80% of new mutations. Male fetuses inheriting this mutation and other "null" mutations of NEMO usually die in utero. Less deleterious mutations can result in survival of males subjects, but with ectodermal dysplasia and immunodeficiency. Male patients with skin, dental, and ocular abnormalities typical of those seen in female patients with IP (without immunodeficiency) are rare. We investigated four male patients with clinical hallmarks of IP. All four were found to carry the deletion normally associated with male lethality in utero. Survival in one patient is explained by a 47,XXY karyotype and skewed X inactivation. Three other patients possess a normal 46,XY karyotype. We demonstrate that these patients have both wild-type and deleted copies of the NEMO gene and are therefore mosaic for the common mutation. Therefore, the repeat-mediated rearrangement leading to the common deletion does not require meiotic division. Hypomorphic alleles, a 47,XXY karyotype, and somatic mosaicism therefore represent three mechanisms for survival of males carrying a NEMO mutation.

Alleles↗
PubMed2001

Large-scale deletions and SMADIP1 truncating mutations in syndromic Hirschsprung disease with involvement of midline structures.

Hirschsprung disease (HSCR) is a common malformation of neural-crest-derived enteric neurons that is frequently associated with other congenital abnormalities. The SMADIP1 gene recently has been recognized as disease causing in some patients with 2q22 chromosomal rearrangement, resulting in syndromic HSCR with mental retardation, with microcephaly, and with facial dysmorphism. We screened 19 patients with HSCR and mental retardation and eventually identified large-scale SMADIP1 deletions or truncating mutations in 8 of 19 patients. These results allow further delineation of the spectrum of malformations ascribed to SMADIP1 haploinsufficiency, which includes frequent features such as hypospadias and agenesis of the corpus callosum. Thus, SMADIP1, which encodes a transcriptional corepressor of Smad target genes, may play a role not only in the patterning of neural-crest-derived cells and of CNS but also in the development of midline structures in humans.

Abnormalities, Multiple↗
PubMed2001

Temporal bone anomaly proposed as a major criteria for diagnosis of CHARGE syndrome.

The acronym CHARGE defines a non-random clustering of congenital malformations of unknown origin. Classical diagnostic criteria include: 1) one major feature namely coloboma/microphthalmia or choanal atresia, and 2) four of the six features designated in the CHARGE acronym. Interestingly, all CHARGE patients hitherto reported had partial or complete semicircular canal hypoplasia on temporal bone CT-scan. We report on semicircular canal agenesis/hypoplasia in three patients with three to four features of the CHARGE syndrome and neither coloboma nor choanal atresia and we propose to include temporal bone malformations as a major criteria for diagnosis of CHARGE syndrome.

Abnormalities, Multiple↗
PubMed2001

Impaired autonomic control of the heart by SOX10 mutation.

The autonomic nervous system plays an important role in the generation of complex heart rate dynamics that enable an organism to adapt to stress. Little is known about genes influencing the development of this autonomic control of the heart. We suggest the SOX10 gene to be a candidate for this process.

Adolescent↗
PubMed2001

A novel automated strategy for screening cryptic telomeric rearrangements in children with idiopathic mental retardation.

Cryptic unbalanced subtelomeric rearrangements are known to cause a significant proportion of idiopathic mental retardation in childhood. Because of the limited sensitivity of routine analyses, the cytogenetic detection of such rearrangements requires molecular techniques, namely FISH and comparative genomic hybridisation (CGH). An alternative approach consists in using genetic markers to detect segmental aneusomy. Here, we describe a new strategy based upon automated fluorescent genotyping to search for non mendelian segregation of telomeric microsatellites. A total of 29 individuals belonging to 24 unrelated families were screened and three abnormal patterns of segregation were detected (two rearrangements and one parental disomy). This study gives strong support to the view that cryptic telomeric rearrangements significantly contribute to idiopathic mental retardation and demonstrates that fluorescent genotyping is a very sensitive and cost-effective method to detect deletions, duplications and uniparental disomies.

Child↗
PubMed2001

TP63 gene mutation in ADULT syndrome.

TP63 gene mutations have recently been shown to be disease causing in EEC and SHFM. Two other overlapping syndromes with ectrodactyly as a major feature, have been mapped to chromosome 3q27 close by the TP63 locus, namely the LMS and ADULT syndromes. Here, we report on a missense TP63 gene mutation in an isolated ADULT syndrome case. This finding widens the spectrum of abnormalities to be ascribed to TP63 gene in human and emphasise on the variable roles of the different Tp63 isotypes.

Abnormalities, Multiple↗
PubMed2001

PAX2 mutations in oligomeganephronia.

BACKGROUND: Oligomeganephronia (OMN) is a rare congenital and usually sporadic anomaly. It is characterized by bilateral renal hypoplasia, with a reduced number of enlarged nephrons. The mechanisms involved in this deficient nephrogenesis are unknown. The paired box transcription factor PAX2 plays a fundamental role in renal development. Heterozygous Pax2 mutants in mice are characterized by renal hypoplasia and retinal defects, and in humans, PAX2 mutations have been described in the renal-coloboma syndrome. METHODS: To assess whether OMN could be related to PAX2, we searched for PAX2 mutations in nine patients presenting with sporadic and apparently isolated OMN. RESULTS: Heterozygous PAX2 mutations were found in three patients. A limited optic nerve coloboma was secondarily detected in two cases and a very mild optic disk dysplasia in one patient. None of these patients had visual impairment. CONCLUSIONS: Ocular anomaly and PAX2 mutations should be sought in all patients with OMN.

Adolescent↗