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Biomedical subjects

D Sillence

Publications and source records attributed to D Sillence.

At least 19 recordsLinked to original sources
PubMed2001

Twelve novel mutations in the tissue-nonspecific alkaline phosphatase gene (ALPL) in patients with various forms of hypophosphatasia.

Hypophosphatasia is a rare inherited disorder characterized by defective bone mineralization and deficiency of serum and tissue liver/bone/kidney tissue alkaline phosphatase (L/B/K ALP) activity. We report here the characterization of tissue-nonspecific alkaline phosphatase (TNSALP) gene mutations in a series of 11 families affected by various forms of hypophosphatasia. Nineteen distinct mutations were found, 7 of which were previously reported. Eleven of the 12 new mutations were missense mutations (Y11C, A34V, R54H, R135H, N194D, G203V, E218G, D277Y, F310G, A382S, V406A), the last one (998-1G>T) was a mutation affecting acceptor splice site.

Adult↗
PubMed2000

Huntington's disease: neurological assessment of potential gene carriers presenting for predictive DNA testing.

One hundred and fifty-six potential gene carriers who were 50% 'at risk' of inheriting the Huntington's disease (HD) mutation, and who presented for predictive testing, underwent neurological assessment before their gene status had been determined. The association between pre-gene result symptoms and minimal neurological signs (insufficient for diagnosis in their own right) and subsequent gene status was determined. Of these, 38% tested positive for the HD mutation. Fifty-one individuals had minor neurological signs. After exclusions, 61% of gene-positive patients had minor neurological signs, whereas only 8% testing gene negative had signs. Minimal chorea observed in the toes and feet with the subject supine, and the patient being stressed by a mental task carried 96% specificity and 86% positive predictive value for gene-positive status. Neurological symptoms did not distinguish gene status, but behavioural and cognitive symptoms were more often reported by the gene-positive group. Although an 'at-risk' individual may receive a gene-positive result, neurological examination remains the most accessible, reliable and cost effective means of determining clinical disease onset.

Adult↗
PubMed2000

Type 2 Gaucher disease: the collodion baby phenotype revisited.

The association of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase (EC 3.2.1.45), and congenital ichthyosis was first noted a decade ago. Subsequently, a null allele type 2 Gaucher mouse was generated that also exhibited ichthyotic skin, confirming that the skin disorder and enzyme deficiency were directly related. This paper details the clinical and molecular characterisation of 6 cases of type 2 Gaucher disease presenting with the collodion baby phenotype. The identified mutant glucocerebrosidase alleles include two novel mutations (S196P and R131L) and two rare point mutations (R120W and R257Q), as well as alleles resulting from recombination with the nearby glucocerebrosidase pseudogene. There is significant genotypic heterogeneity in this rare subset of patients with type 2 Gaucher disease. Gaucher disease should be considered in the differential diagnosis of congenital ichthyosis in the newborn period.

Blotting, Southern↗
PubMed2000

Evidence for digenic inheritance in some cases of Antley-Bixler syndrome?

The Antley-Bixler syndrome has been thought to be caused by an autosomal recessive gene. However, patients with this phenotype have been reported with a new dominant mutation at the FGFR2 locus as well as in the offspring of mothers taking the antifungal agent fluconazole during early pregnancy. In addition to the craniosynostosis and joint ankylosis which are the clinical hallmarks of the condition, many patients, especially females, have genital abnormalities. We now report abnormalities of steroid biogenesis in seven of 16 patients with an Antley-Bixler phenotype. Additionally, we identify FGFR2 mutations in seven of these 16 patients, including one patient with abnormal steroidogenesis. These findings, suggesting that some cases of Antley-Bixler syndrome are the outcome of two distinct genetic events, allow a hypothesis to be formulated under which we may explain all the differing and seemingly contradictory circumstances in which the Antley-Bixler phenotype has been recognised.

Abnormalities, Drug-Induced↗
PubMed1999

Variability in kyphomelic dysplasia.

Four infants with kyphomelic dysplasia ascertained from three families demonstrate variability within the syndrome. In the first family, sibling recurrence in female sibs was noted with atypical kyphomelic dysplasias, suggesting autosomal recessive inheritance. In the second family, with a male affected with the 'typical findings' of lethal kyphomelic dysplasia, diagnosis of a skeletal dysplasia was suspected at 29-30 weeks' gestation following US detection of short, bent femurs. In the third family, with a female affected, severe radiographic changes were documented at birth. The clinical course of the disease was mild with almost complete regression of the radiographic findings at the age of 7 years.

Abortion, Induced↗
PubMed1999

Transport of (glyco)sphingolipids in and between cellular membranes; multidrug transporters and lateral domains.

Sphingolipids are highly enriched in the outer leaflet of the plasma membrane lipid bilayer. However, the first glycolipid, glucosylceramide, is synthesized in the opposite, cytosolic leaflet of the Golgi membrane. This has led us to experiments which suggest that the level of glucosylceramide in the cytosolic surface is carefully regulated both by the balance between synthesis and hydrolysis and by transport away from this surface through translocators, multidrug transporters, the same molecules that make cancer cells resistant to chemotherapy. Our data suggest a role for newly synthesized glucosylceramide not only in the formation of domains in the luminal leaflet of the Golgi but also on the cytosolic surface of this organelle.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Identification of the gene (SEDL) causing X-linked spondyloepiphyseal dysplasia tarda.

Spondyloepiphyseal dysplasia tarda (SEDL; MIM 313400) is an X-linked recessive osteochondrodysplasia that occurs in approximately two of every one million people. This progressive skeletal disorder which manifests in childhood is characterized by disproportionate short stature with short neck and trunk, barrel chest and absence of systemic complications. Distinctive radiological signs are platyspondyly with hump-shaped central and posterior portions, narrow disc spaces, and mild to moderate epiphyseal dysplasia. The latter usually leads to premature secondary osteoarthritis often requiring hip arthroplasty. Obligate female carriers are generally clinically and radiographically indistinguishable from the general population, although some cases have phenotypic changes consistent with expression of the gene defect. The SEDL gene has been localized to Xp22 (refs 8,9) in the approximately 2-Mb interval between DXS16 and DXS987 (ref. 10). Here we confirm and refine this localization to an interval of less than 170 kb by critical recombination events at DXS16 and AFMa124wc1 in two families. In one candidate gene we detected three dinucleotide deletions in three Australian families which effect frameshifts causing premature stop codons. The gene designated SEDL is transcribed as a 2.8-kb transcript in many tissues including fetal cartilage. SEDL encodes a 140 amino acid protein with a putative role in endoplasmic reticulum (ER)-to-Golgi vesicular transport.

Adolescent↗
PubMed1999

Basilar impression complicating osteogenesis imperfecta type IV: the clinical and neuroradiological findings in four cases.

OBJECTIVES: To describe the clinical and neuroradiological features of basilar impression in patients with osteogenesis imperfecta type IV. METHODS: Four patients with basilar impression were ascertained in a population study of osteogenesis imperfecta. All four had detailed clinical and neuroradiological examination with both CT and MRI of the craniocervical junction and posterior fossa structures. RESULTS: All four showed significant compression of the posterior fossa structures and surgical decompression was performed with relief of symptoms. CONCLUSION: Symptoms of cough headache and trigeminal neuralgia occurring in patients with osteogenesis imperfecta are indications for detailed clinical and neuroradiological investigation to document basilar impression.

Adolescent↗
PubMed1998

Gene localization for an autosomal dominant familial periodic fever to 12p13.

We report gene localization in a family with a benign autosomal dominant familial periodic fever (FPF) syndrome characterized by recurrent fever associated with abdominal pain. The clinical features are similar to the disorder previously described as familial Hibernian fever, and they differ from familial Mediterranean fever (FMF) in that FPF episodes usually do not respond to colchicine and FPF is not associated with amyloidosis. Frequent recombination with the marker D16S2622, <1 Mb from FMF, at 16p13.3, excluded allelism between these clinically similar conditions. Subsequently, a semiautomated genome search detected linkage of FMF to a cluster of markers at 12p13, with a multipoint LOD score of 6.14 at D12S356. If penetrance of 90% is assumed, the FPF gene maps to a 19-cM interval between D12S314 and D12S364; however, if complete penetrance is assumed, then FPF maps to a 9-cM region between D12S314 and D12S1695. This interval includes the dentatorubropallidoluysian atrophy locus, which, with FPF, gave a maximum two-point LOD score of 3.7 at a recombination fraction of 0. This is the first of the periodic-fever genes, other than FMF, to be mapped. Positional candidate genes may now be selected for mutation analysis to determine the molecular basis for FPF. Together with the recent identification of the defective gene in FMF, identification of a gene for FPF might provide new insights into the regulation of inflammatory responses.

Chromosome Mapping↗
PubMed1998

Medical complications of achondroplasia: a multicentre patient review.

Achondroplasia is the most prevalent chondrodysplasia and numerous authors have documented the varied social and medical complications that may compromise a full and productive life. Complications include cervicomedullary compression, spinal stenosis, restrictive and obstructive lung disease, otitis media, and tibial bowing, among others. These known complications have led to recommendations for the anticipatory management of such patients. There are relatively few data on the actual rates and timing of these problems. This paper reports data on the rates and age of occurrence of several of these complications based on a review of recorded chart information of 193 patients ascertained from several well established genetic centres with a known interest in the chondrodysplasias. The length of follow up varied and the rates of occurrence at specific age intervals were used to estimate the cumulative percentage affected for each complication. The report includes information on otitis media, ventilation tubes, hearing loss, tonsillectomy, speech problems, tibial bowing and osteotomy, ventricular shunting, apnoea, cervicomedullary decompression, and neurological signs attributable to spinal stenosis.

Achondroplasia↗
PubMed1997

The subcellular sites of sphingomyelin synthesis in BHK cells.

The subcellular distributions of the enzymes which synthesise sphingomyelin (SM) and glucosylceramide (GluCer) from ceramide have been assessed in BHK cells. On a sucrose density gradient GluCer synthase (a marker of the cis/medial Golgi apparatus) and the trans-Golgi marker galactosyltransferase showed an similar monotonic distribution. In contrast, SM synthase showed two peaks of activity, a minor one which migrated with the Golgi markers and a major one which had a density close to that of plasma membrane markers (sphingomyelin, cholesterol, PtdSer, ganglioside GM3 and alkaline phosphodiesterase). When cell homogenates were treated with digitonin, the sedimentation characteristics of the Golgi markers was largely unaffected whereas the plasma membrane markers and the main peak of SM synthase activity were shifted to higher density. In contrast, when cells were treated with brefeldin A (BFA) the Golgi markers were shifted to higher density but not the plasma membrane markers or the main peak of SM synthase. These results suggest that the bulk of SM synthase activity in BHK cells is not associated with the Golgi cisternae but with a cell compartment which is relatively rich in cholesterol (e.g., plasma membrane, endosomes or trans-Golgi network.) Further experiments in which cells were treated with sphingomyelinase provided evidence that SM synthase activity was in an internal compartment and not at the plasma membrane.

Animals↗
PubMed1997

Atelosteogenesis syndromes: a review, with comments on their pathogenesis.

The clinical, radiographic, and morphological findings in 25 cases of atelosteogenesis and boomerang dysplasia have been reviewed. The review confirms the nosologic grouping of atelosteogenesis type I with boomerang dysplasia and the clinical and radiographic overlap of features between atel- osteogenesis I and atelosteogene- sis II (synonymous with De la Chapelle dysplasia) and a group of patients with atelosteogenesis type III. A common pathogenesis is suggested for atelosteogenesis type I and boomerang dysplasia. A marked excess of male fetuses with boomerang dysplasia was observed. Atelosteogenesis type II shows distinctive chondro-osseous histopathology with a major disturbance in cartilage matrix macromolecules. An overlap of phenotypic, radiographic, morphological, and cartilage histochemical features with those observed in diastrophic dysplasia and achondrogenesis type IB suggests that atelosteogenesis type II has common pathogenetic features with disorders of sulfation of connective tissue matrix macro- molecules.

Bone Diseases, Developmental↗
PubMed1997

Contribution of DNA sequence and CAG size to mutation frequencies of intermediate alleles for Huntington disease: evidence from single sperm analyses.

New mutations for Huntington disease (HD) arise from intermediate alleles (IAs) with between 29 and 35 CAG repeats that expand on transmission through the paternal germline to 36 CAGs or greater. Using single sperm analysis, we have assessed CAG mutation frequencies for four IAs in families with sporadic HD (IANM) and IAs ascertained from the general population (IAGP) by analyzing 1161 single sperm from three persons. We show that IANM are more unstable than IAGP with identical size and sequence. Furthermore, comparison of different sized IAs and IAs with different sequences between the CAG and the adjacent CCG tracts indicates that DNA sequence is a major influence on CAG stability. These studies provide estimates of the likelihood of expansion of IANM and IAGP to > or = 36 CAG repeats for these individuals. For an IA with a CAG of 35 in this family with sporadic HD, the likelihood for siblings to inherit a recurrent mutation > or = 36 CAG is approximately 10%. For IAGP of a similar size, the risk of inheriting an expanded allele of > or = 36 CAG through the paternal germline is approximately 6%. These risk estimates are higher than previously reported and provide additional information for counselling in these families. Further studies on persons with IAs will be needed to determine whether these results can be generalized to other families.

Alleles↗
PubMed1997

Human mucopolysaccharidosis IIID: clinical, biochemical, morphological and immunohistochemical characteristics.

Mucopolysaccharidosis IIID (MPS IIID) is one of the rarest of the MPS-III syndromes. To date, the clinical manifestations of 10 patients have been reported, the deficient N-acetylglucosamine 6-sulfatase (G6S) enzyme has been purified, and the G6S gene has been cloned, sequenced and localized. However, morphological manifestations of this condition have not been reported and the pathogenesis of the severe neurological deficits remains an enigma. In this paper we describe and correlate the clinical, biochemical and pathological observations for 2 cases of MPS IIID. We used monoclonal antibodies against heparan sulfate (HS) and GM2-ganglioside, thin layer chromatography, mass spectrometry, and morphological techniques to demonstrate the nature and the distribution of the uncatabolized substrates. The majority of the cells in various tissues showed morphological changes expected with lysosomal storage of HS. The central nervous system (CNS) was most severely affected because of the secondary storage of GM2 and GM3 gangliosides in addition to the primary accumulation of HS. The extent as well as the distribution of the diverse storage materials varied within and among different neurons as observed in MPS-III A, B, and C syndromes. This study supports the hypothesis that the neurological dysfunction and neurodegeneration common to the Sanfilippo syndromes is, in part, due to the secondary metabolic perturbations induced by HS accumulation.

Adolescent↗
PubMed1995

Early prenatal diagnosis of cartilage-hair hypoplasia (CHH) with polymorphic DNA markers.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive disorder resulting in short stature and hypoplasia of hair. Associated features include impaired T-cell-mediated immunity, deficient erythropoiesis, gastrointestinal dysfunction, and an increased risk of malignancies. As the condition may, in some cases, be severe or even fatal during childhood, families with a previous history of CHH may wish to have prenatal diagnosis. We have previously assigned the gene for CHH to the proximal 9p by linkage analysis using several polymorphic DNA markers. Here we report the prenatal testing for CHH in three Finnish and one Australian family using three DNA markers closely linked to the CHH gene. In three cases a fetus unaffected with CHH was predicted at the probability level of more than 94 per cent. In one case, an affected fetus was predicted. The results were in concordance with ultrasonography performed for all fetuses. The three children born to date were unaffected as predicted. The DNA marker-based analysis thus provides a useful method for early prenatal testing for CHH.

Base Sequence↗
PubMed1995

Genetic homogeneity of cartilage-hair hypoplasia.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive metaphyseal chondrodysplasia characterized by short stature and hypoplasia of the hair. Associated pleiotropic features include deficient erythrogenesis, impaired T-cell mediated immunity, Hirschsprung's disease, and an increased risk of malignancies. CHH is most prevalent among the Old Order Amish in the United States and among the Finns, but sporadic families have been described among many other populations. We have previously mapped the gene for CHH to the short arm of chromosome 9 in Finnish and Amish families. The CHH locus resides close to D9S163 within an interval of 1.5 cM flanked by D9S165 and D9S50. In order to investigate the genetic homogeneity of CHH in various populations, we studied nine families with no genealogical connections to either Amish or Finns. No recombinants were detected between the CHH gene and any of the three closest marker loci studied, suggesting that CHH in these families results from mutation(s) at the same locus as in the Amish and Finnish families.

Canada↗
PubMed1995

Increased instability of intermediate alleles in families with sporadic Huntington disease compared to similar sized intermediate alleles in the general population.

We have directly compared intergenerational stability of intermediate alleles (IAs) derived from new mutation families (IANM) for Huntington disease (HD) with IAs in the general population (IAGP) which occur in approximately 1 in 50 persons. Analysis of meiotic events in blood and sperm reveals that IANM are significantly more unstable than IAGP despite similar size. However, for both IANM and IAGP CAG changes were small and risks for inheriting an expansion into the HD affected range were low. Sequence analysis reveals that the CAG tract is generally interrupted by a penultimate CAA in IAGP, IANM and alleles in the affected range. In one new mutation family, however, two A-->G mutations result in a pure CAG tract which is associated with very marked instability. These mutations alter the predicted DNA hairpin structure with a predicted increase in the likelihood of large expansion, supporting the model that hairpin loop formation plays an important role in trinucleotide instability.

Alleles↗