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Jean-Pierre Fryns

Publications and source records attributed to Jean-Pierre Fryns.

At least 37 records · Page 2Linked to original sources
PubMed2006

The genetic basis of the Pierre Robin Sequence.

OBJECTIVE: The Pierre Robin Sequence (PRS) is subgroup of the cleft palate population. As with the etiology of cleft lip or palate, the etiology of PRS is generally unknown. Some factors are suggestive of a genetic basis for PRS. The purpose of this study was to compare genetic information on PRS available in the literature and in a cytogenetic database to facilitate focused genetic studies of PRS. DESIGN: After searching Medline for "pierre robin and genetics," the Mendelian Cytogenetics Network database for "robin" and "pierre robin," and two reviews from the Human Cytogenetics Database for "cleft palate" and "micrognathia," a comparison of the data and a search in Online Mendelian Inheritance in Man (OMIM) Gene Map was performed to identify relevant candidate genes. RESULTS: The findings revealed consistency to a certain degree to loci 2q24.1-33.3, 4q32-qter, 11q21-23.1, and 17q21-24.3. A search in the OMIM Gene Map provided many candidate genes for PRS in these regions. The GAD67 on 2q31, the PVRL1 on 11q23-q24, and the SOX9 gene on 17q24.3-q25.1 are suggested to be of particular importance. CONCLUSION: Candidate loci and a few potential candidate genes for PRS are proposed from the present study. This may enable researchers to focus their effort in the studies of PRS.

Cleft Lip↗
PubMed2006

Focal segmental glomerulosclerosis in patients with mandibuloacral dysplasia owing to ZMPSTE24 deficiency.

BACKGROUND: Mandibuloacral dysplasia (MAD) is a rare autosomal recessive disorder characterized by skeletal abnormalities such as hypoplasia of the mandible and clavicles and acro-osteolysis. Other features include cutaneous atrophy and lipodystrophy. Two genetic loci are known for MAD: lamin A/C (LMNA), encoding structural nuclear lamina proteins, and zinc metalloproteinase (ZMPSTE24), a membrane-bound endoprotease involved in post-translational proteolytic cleavage of carboxy terminal residues of prelamin A to form mature lamin A. METHODS: Mutational analysis of ZMPSTE24 in an additional patient with MAD and determination of functional activity of mutant ZMPSTE24 in a yeast growth arrest pheromone diffusion (halo) assay. RESULTS: We previously reported a Belgian woman with MAD who had ZMPSTE24 mutations and died of complications of chronic renal failure at the age of 27.5 years. We now report a 37-year-old Australian man with MAD who also had compound heterozygous mutations in the ZMPSTE24 gene, a null mutation, Phe361fsX379, and a missense mutation, Asn265Ser, which is partially active in the yeast complementation assay. He also developed end-stage renal disease and, despite receiving a cadaveric renal transplantation, died prematurely at the age of 37 years. Renal biopsies of both patients revealed focal segmental glomerulosclerosis, and the female patient had the collapsing variant. CONCLUSION: These observations suggest focal segmental glomerulosclerosis as a phenotypic manifestation in patients with ZMPSTE24 deficiency.

Acro-Osteolysis↗
PubMed2005

ZNF674: a new kruppel-associated box-containing zinc-finger gene involved in nonsyndromic X-linked mental retardation.

Array-based comparative genomic hybridization has proven to be successful in the identification of genetic defects in disorders involving mental retardation. Here, we studied a patient with learning disabilities, retinal dystrophy, and short stature. The family history was suggestive of an X-linked contiguous gene syndrome. Hybridization of full-coverage X-chromosomal bacterial artificial chromosome arrays revealed a deletion of ~1 Mb in Xp11.3, which harbors RP2, SLC9A7, CHST7, and two hypothetical zinc-finger genes, ZNF673 and ZNF674. These genes were analyzed in 28 families with nonsyndromic X-linked mental retardation (XLMR) that show linkage to Xp11.3; the analysis revealed a nonsense mutation, p.E118X, in the coding sequence of ZNF674 in one family. This mutation is predicted to result in a truncated protein containing the Kruppel-associated box domains but lacking the zinc-finger domains, which are crucial for DNA binding. We characterized the complete ZNF674 gene structure and subsequently tested an additional 306 patients with XLMR for mutations by direct sequencing. Two amino acid substitutions, p.T343M and p.P412L, were identified that were not found in unaffected individuals. The proline at position 412 is conserved between species and is predicted by molecular modeling to reduce the DNA-binding properties of ZNF674. The p.T343M transition is probably a polymorphism, because the homologous ZNF674 gene in chimpanzee has a methionine at that position. ZNF674 belongs to a cluster of seven highly related zinc-finger genes in Xp11, two of which (ZNF41 and ZNF81) were implicated previously in XLMR. Identification of ZNF674 as the third XLMR gene in this cluster may indicate a common role for these zinc-finger genes that is crucial to human cognitive functioning.

Amino Acid Sequence↗
PubMed2005

A homozygous mutation in the lamin A/C gene associated with a novel syndrome of arthropathy, tendinous calcinosis, and progeroid features.

CONTEXT: Mutations in the lamin A/C (LMNA) gene have been reported in a wide variety of disorders, including lipodystrophies, cardiomyopathy, muscular dystrophies, neuropathy, mandibuloacral dysplasia, restrictive dermopathy, and progeria. OBJECTIVE: The objective of this study was to carry out mutational analysis of LMNA in a patient with a novel syndrome of arthropathy, tendinous calcinosis, and progeroid features. DESIGN: The study design was a descriptive case report. SETTING: The study was performed at a referral center. PATIENT: A 44-yr-old male of European descent with an autosomal recessive arthropathy syndrome affecting predominantly the distal femora and proximal tibia in the knee with tendinous calcifications was studied. He also had progeroid features, such as pinched nose and micrognathia, cataract, alopecia, generalized lipodystrophy, and sclerodermatous skin. MAIN OUTCOME MEASURES: The main outcome measures were mutational analysis of lamin A/C (LMNA) and its processing enzyme, zinc metalloproteinase (ZMPSTE24), as candidate genes. RESULTS: We found a homozygous nucleotide substitution, 1718C>T, in exon 11 of the LMNA gene, resulting in substitution of a well-conserved residue serine at position 573 with leucine (S573L). This missense mutation only affects lamin A, not lamin C, because the alternative splicing site is located in exon 10. Immunofluorescence staining of the nuclei from his skin fibroblasts showed occasional misshapen morphology. CONCLUSIONS: The S573L homozygous LMNA mutation is associated with a novel phenotype of arthropathy, tendinous calcifications, and progeroid features distinct from the acroosteolysis previously reported in patients with mandibuloacral dysplasia caused by LMNA or ZMPSTE24 mutations. Thus, arthropathy with tendinous calcifications can be added to the growing list of disorders associated with LMNA mutations.

Adult↗
PubMed2005

Disruptions of the novel KIAA1202 gene are associated with X-linked mental retardation.

The extensive heterogeneity underlying the genetic component of mental retardation (MR) is the main cause for our limited understanding of the aetiology of this highly prevalent condition. Hence we set out to identify genes involved in MR. We investigated the breakpoints of two balanced X;autosome translocations in two unrelated female patients with mild/moderate MR and found that the Xp11.2 breakpoints disrupt the novel human KIAA1202 (hKIAA1202) gene in both cases. We also identified a missense exchange in this gene, segregating with the Stocco dos Santos XLMR syndrome in a large four-generation pedigree but absent in >1,000 control X-chromosomes. Among other phenotypic characteristics, the affected males in this family present with severe MR, delayed or no speech, seizures and hyperactivity. Molecular studies of hKIAA1202 determined its genomic organisation, its expression throughout the brain and the regulation of expression of its mouse homologue during development. Transient expression of the wild-type KIAA1202 protein in HeLa cells showed partial colocalisation with the F-actin based cytoskeleton. On the basis of its domain structure, we argue that hKIAA1202 is a new member of the APX/Shroom protein family. Members of this family contain a PDZ and two ASD domains of unknown function and have been shown to localise at the cytoskeleton, and play a role in neurulation, cellular architecture, actin remodelling and ion channel function. Our results suggest that hKIAA1202 may be important in cognitive function and/or development.

Amino Acid Sequence↗
PubMed2005

Duplication of the MECP2 region is a frequent cause of severe mental retardation and progressive neurological symptoms in males.

Loss-of-function mutations of the MECP2 gene at Xq28 are associated with Rett syndrome in females and with syndromic and nonsyndromic forms of mental retardation (MR) in males. By array comparative genomic hybridization (array-CGH), we identified a small duplication at Xq28 in a large family with a severe form of MR associated with progressive spasticity. Screening by real-time quantitation of 17 additional patients with MR who have similar phenotypes revealed three more duplications. The duplications in the four patients vary in size from 0.4 to 0.8 Mb and harbor several genes, which, for each duplication, include the MR-related L1CAM and MECP2 genes. The proximal breakpoints are located within a 250-kb region centromeric of L1CAM, whereas the distal breakpoints are located in a 300-kb interval telomeric of MECP2. The precise size and location of each duplication is different in the four patients. The duplications segregate with the disease in the families, and asymptomatic carrier females show complete skewing of X inactivation. Comparison of the clinical features in these patients and in a previously reported patient enables refinement of the genotype-phenotype correlation and strongly suggests that increased dosage of MECP2 results in the MR phenotype. Our findings demonstrate that, in humans, not only impaired or abolished gene function but also increased MeCP2 dosage causes a distinct phenotype. Moreover, duplication of the MECP2 region occurs frequently in male patients with a severe form of MR, which justifies quantitative screening of MECP2 in this group of patients.

Chromosomes, Human, X↗
PubMed2005

Acrofacial dysostosis type Rodríguez.

The acrofacial dysostoses (AFD) are a clinically and causally heterogeneous group of conditions characterized by mandibulofacial dysostosis and a variety of limb anomalies. Several abnormalities affecting different internal organs and the central nervous system (CNS) have been described. Depending on the type of limb defects, two major groups have been delineated: (1) with predominantly pre-axial anomalies, Nager type AFD, and (2) with predominantly post-axial involvement, Genee-Wiedemann form of AFD, also known as POADS, respectively. Other forms of "true AFD" have been described as Kelly, Reynolds, Arens (also Tel Aviv form), Rodríguez (or Madrid form), Richieri-Costa, and Patterson-Stevenson-Fontaine types. However, whether they are distinct entities or represent variants of the same condition remains unclear. Rodríguez AFD was described as a new lethal form of AFD in three affected sibs with severe mandibular hypoplasia, severe predominantly pre-axial limb deficiencies, absent fibulae and ribs, and internal organ anomalies, the most remarkable of which are arrhinencephaly and abnormal lung lobulation. We present a newborn girl with Rodríguez type of AFD, who died a few days after the birth due to respiratory failure. The phenotype and the cause of this condition are discussed.

Abnormalities, Multiple↗
PubMed2005

Deletion of VCX-A due to NAHR plays a major role in the occurrence of mental retardation in patients with X-linked ichthyosis.

X-linked ichthyosis (XLI) is often associated with a recurrent microdeletion at Xp22.31 due to non-allelic homologous recombination between the CRI-S232 low-copy repeat regions flanking the STS gene. The clinical features of these patients may include mental retardation (MR) and the VCX-A gene has been proposed as the candidate MR gene. Analysis of DNA from four XLI patients with MR by array-comparative genomic hybridization (array-CGH) on a 150 kb resolution X chromosome-specific array revealed a 1.5 Mb interstitial microdeletion with breakpoints in the CRI-S232 repeat sequences, each of which harbors a VCX gene. We demonstrate that the recombination sites in all four cases are situated in the 1 kb repeat unit 2 region present at the 3' ends of the VCX-A and VCX-B genes thereby deleting VCX-A and VCX-B1 but not VCX-B and VCX-C. Array-CGH with DNA of an XLI patient with MR and an inherited t(X;Y)(p22.31;q11.2) showed an Xpter deletion of 8.0 Mb resulting in the deletion of all four VCX genes and duplication of both VCY homologs. These data confirm the role of VCX-A in the occurrence of MR in XLI patients. Moreover, we propose a VCX/Y teamwork-dependent mechanism for the incidence of mental impairment in XLI patients.

Chromosomes, Human, X↗
PubMed2005

Carpal and tarsal synostoses and transverse reduction defects of the toes in two brothers heterozygous for a double de novo NOGGIN mutation.

We describe two siblings with carpal and tarsal synostoses associated with transverse deficiencies of the toes. Mutation analysis of the NOG gene revealed a double missense mutation in both boys resulting in Pro42Ala and Pro50Arg. The parents were clinically unaffected, and these two mutations were not detected in their white blood cells or buccal mucosa. This indicates the presence of gonadal mosaicism or a low level of somatic mosaicism in one of the parents.

Abnormalities, Multiple↗
PubMed2005

Follow-up of adult males with chromosome 18p deletion.

The 18p- syndrome has been known for over 40 years, the first report being by de Grouchy et al. [Comptes Rendus Hebdomadaires Séances l'Acad Sci 256 (1963) 1028]. Mental retardation of varying severity is the most constant feature. Over 100 cases have been reported. The eldest patients have been 50 years [Hum Genet 63 (1983) 139; Clin Genet 2 (1971) 338]. Follow-up of two adult patients, then 22 and 42 years [Ann Génét 29 (1986) 107], now 42 and 62 years of age, is reported. Further case reports are required in order to better define the evolution of adult patients with the 18p- syndrome.

Abnormalities, Multiple↗
PubMed2005

X-linked mental retardation, short stature, microcephaly and hypogonadism maps to Xp22.1-p21.3 in a Belgian family.

X-linked mental retardation (XLMR) is a heterogeneous disorder that can be classified as either non-specific (MRX), when mental retardation is the only feature, or as syndromic mental retardation (MRXS). Genetic defects underlying XLMR are being identified at a rapid pace, often starting from X-chromosomal aberrations and XLMR families with a well-defined linkage interval. Here, we present a new family with a syndromic form of XLMR, including mild mental retardation, short stature, microcephaly and hypogonadism. Two-point linkage analysis with 24 polymorphic markers spanning the entire X chromosome was carried out. We could assign the causative gene to a 6 cM interval in Xp22.1-p21.3, with a maximum LOD score of 2.61 for markers DXS989 and DXS1061 at theta = 0.00. No mutations were found in the presented family for two known MRX genes mapping to this interval, ARX and IL1RAPL-1. These data indicate that the interval Xp22.1-p21.3 contains at least one additional MRXS gene.

Adult↗
PubMed2005

Large deletions of the APC gene in 15% of mutation-negative patients with classical polyposis (FAP): a Belgian study.

Germline mutations of the APC gene are responsible for familial adenomatous polyposis (FAP). Most of the mutations are protein truncating mutations and are spread over the coding region. Rare whole-gene deletions or exonic deletions have been described. From a series of 85 patients clinically diagnosed with FAP or attenuated FAP (AAPC) in our center, 30 (35%) were found to have truncating or missense mutations. We have now screened the remaining 55 patients for exonic deletions or duplications, first by semi-quantitative PCR and later by multiplex ligation-dependent probe amplification (MLPA). Three whole-gene deletions and one exon 14 deletion were found (5% of patients). The whole-gene deletions were confirmed by fluorescence in situ hybridization (FISH) analysis, and the breakpoints of the exon 14 deletion could be determined using long range PCR. Further characterization of the whole gene deletions was performed using extragenic polymorphic markers and/or semi-quantitative PCR. We could demonstrate that the deletions do not encompass the MCC gene. Interestingly, the phenotype of the deletion patients was not different from that of patients with truncating mutations. The polyp numbers ranged from attenuated to profuse polyposis and the interfamilial variability of disease phenotype was as in other FAP families. In none of the 28 AAPC patients included in this study, was a large deletion found, while 15% of the patients with classical polyposis had a genomic deletion. It corroborates recently published data, suggesting that large deletions may occur with a frequency higher than 10% in mutation-negative patients with a classical polyposis. In this article, we have included an overview of genomic rearrangements in the 5q21 region.

Adenomatous Polyposis Coli↗
PubMed2005

Early motor development in young children with 22q.11 deletion syndrome and a conotruncal heart defect.

Velocardiofacial syndrome is identified by a submicroscopic deletion of chromosome 22q.11 (del22q.11). This study presents data on the early motor development and behaviour of 11 children (8 males, 3 females) with del22q.11 (mean age 41mo, SD 9.7mo) with a congenital heart defect. To control for the impact of the congenital heart defect, a control group of 19 children (15 males, 4 females; mean age 46mo, SD 9mo) with the same types of congenital heart defects but without del22q.11 was selected. Motor development in both groups was measured with the Peabody Developmental Motor Scales-2. Behaviour was assessed with the Child Behaviour Checklist. Children with del22q.11 scored significantly lower (p<0.05) on motor performance than the children of the control group. Most deficient motor skills were found for the subtests Locomotion and Stationary. On the behaviour questionnaire, a statistically significant (p<0.05) difference between the two groups was found only for the subscale Withdrawn. These data reveal a significant motor delay in many young children with del22q.11, which is not caused by the presence of a congenital heart defect or by behavioural features.

Case-Control Studies↗
PubMed2005

Screening for FMR-1 premutations in 122 older Flemish males presenting with ataxia.

Recently, Hagerman et al described the occurrence of a late-onset neurological disorder in five male carriers of the fragile-X (FMR-1) premutation. The major characteristics of this disorder, designated the Fragile-X Tremor Ataxia Syndrome (FXTAS), are progressive intention tremor, cerebellar ataxia and cognitive decline. Most cases of FXTAS published thus far were ascertained through families with a known fragile-X proband. Since cerebellar ataxia is one of the main cardinal features, we performed FMR-1 premutation screening in 122 male patients, older than 50 years, who were referred to us for testing of the spinocerebellar ataxia (SCA 1, 2, 3, 6, 7) genes and who were found to be negative. In this group of patients, we found five patients with an FMR-1 premutation. In four of them, a definite diagnosis of FXTAS could be made, based on the proposed diagnostic clinical and radiological criteria for FXTAS. In light of these figures, we recommend that FMR-1 analysis should be included in the molecular diagnostic work-up in the group of male ataxia patients older than 50 years.

Aged↗
PubMed2005

A further mutation of the FGFR2 tyrosine kinase domain in mild Crouzon syndrome.

We report a family heterozygous for a newly identified mutation in the tyrosine kinase I domain of the FGFR2 gene (1576A > G, encoding the missense substitution Lys526Glu), associated with variable expressivity of Crouzon syndrome, including clinical nonpenetrance. Our observations expand both the clinical and molecular spectrum of this unusual subset of FGFR2 mutations.

Acrocephalosyndactylia↗