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Biomedical subjects

R M Winter

Publications and source records attributed to R M Winter.

At least 73 records · Page 4Linked to original sources
PubMed1997

A promoter mutation in the XIST gene in two unrelated families with skewed X-chromosome inactivation.

X-chromosome inactivation is the process by which a cell recognizes the presence of two copies of an X chromosome early in the development of XX embryos and chooses one to be active and one to be inactive. Although it is commonly believed that the initiation of X inactivation is random, with an equal probability (50:50) that either X chromosome will be the inactive X in a given cell, significant variation in the proportion of cells with either X inactive is observed both in mice heterozygous for alleles at the Xce locus and among normal human females in the population. Families in which multiple females demonstrate extremely skewed inactivation patterns that are otherwise quite rare in the general population are thought to reflect possible genetic influences on the X-inactivation process. Here we report a rare cytosine to guanine mutation in the XIST minimal promoter that underlies both epigenetic and functional differences between the two X chromosomes in nine females from two unrelated families. All females demonstrate preferential inactivation of the X chromosome carrying the mutation, suggesting that there is an association between alterations in the regulation of XIST expression and X-chromosome inactivation.

Deoxyribonucleases, Type II Site-Specific↗
PubMed1997

The oral-facial-digital syndrome type 1 (OFD1), a cause of polycystic kidney disease and associated malformations, maps to Xp22.2-Xp22.3.

Key features of the oral-facial-digital syndrome type 1 (OFD1) include malformations of the face, oral cavity and digits. In addition, the clinical phenotype often includes mental retardation and renal functional impairment. Approximately 75% of cases of OFD1 are sporadic, and the condition occurs almost exclusively in females. In familial cases, the most likely mode of inheritance is considered to be X-linked dominant with prenatal lethality in affected males. Therefore, the OFD1 gene product appears to have widespread importance in organogenesis and is essential for fetal survival. We have studied two kindreds in which the clinical course was dominated by polycystic kidney disease requiring dialysis and transplantation. Using polymorphic chromosome markers spaced at approximately 10 cM intervals along the X chromosome, we mapped the disease to a region on the short arm of the X chromosome (Xp22.2-Xp22.3) spanning 19.8 cM and flanked by crossovers with the markers DXS996 and DX7S105. There was a maximum lod score of 3.32 in an 'affecteds only' analysis using a marker within the KAL gene (theta = 0.0 ), thereby confirming the location of the gene for OFD1 on the X chromosome. The remainder of the X chromosome was excluded by recombinants in affected individuals. The importance of our findings includes the definitive assignment of this male-lethal disease to the X chromosome and the mapping of a further locus for a human polycystic kidney disease. Furthermore, this mapping study suggests a possible mouse model for OFD1 as the X-linked dominant Xpl mutant, in which polydactyly and renal cystic disease occurs, maps to the homologous region of the mouse X chromosome.

Chromosome Aberrations↗
PubMed1997

The TWIST gene, although not disrupted in Saethre-Chotzen patients with apparently balanced translocations of 7p21, is mutated in familial and sporadic cases.

The TWIST gene maps to 7p21 and mutations in the gene have been reported in the Saethre-Chotzen form of craniosynostosis. The position of the Saethre-Chotzen gene has previously been refined by FISH analysis of four patients carrying balanced translocations involving 7p21 which suggested that it was located between D7S488 and D7S503. We report here that the breakpoints in four translocation patients do not interrupt the coding sequence of the TWIST gene and thus most likely act through a positional effect. Twelve Saethre-Chotzen cases were found to have TWIST mutations. Four of these families had been used as part of the linkage study of the Saethre-Chotzen locus. The mutations detected included missense and nonsense mutations and three cases of a 21 bp duplication. Although phenotypically diagnosed as having Saethre-Chotzen syndrome, three families were found to have a pro250arg mutation of FGFR3.

Acrocephalosyndactylia↗
PubMed1997

Spectrum of clinical features associated with interstitial chromosome 22q11 deletions: a European collaborative study.

We present clinical data on 558 patients with deletions within the DiGeorge syndrome critical region of chromosome 22q11. Twenty-eight percent of the cases where parents had been tested had inherited deletions, with a marked excess of maternally inherited deletions (maternal 61, paternal 18). Eight percent of the patients had died, over half of these within a month of birth and the majority within 6 months. All but one of the deaths were the result of congenital heart disease. Clinically significant immunological problems were very uncommon. Nine percent of patients had cleft palate and 32% had velopharyngeal insufficiency, 60% of patients were hypocalcaemic, 75% of patients had cardiac problems, and 36% of patients who had abdominal ultrasound had a renal abnormality. Sixty-two percent of surviving patients were developmentally normal or had only mild learning problems. The majority of patients were constitutionally small, with 36% of patients below the 3rd centile for either height or weight parameters.

Adolescent↗
PubMed1997

Pendred syndrome: evidence for genetic homogeneity and further refinement of linkage.

Pendred syndrome is the association between congenital sensorineural deafness and goitre. The disorder is characterised by the incomplete discharge of radioiodide from a primed thyroid following perchlorate challenge. However, the molecular basis of the association between hearing loss and a defect in organification of iodide remains unclear. Pendred syndrome is inherited as an autosomal recessive trait and has recently been mapped to 7q31 coincident with the non-syndromic deafness locus DFNB4. To define the critical linkage interval for Pendred syndrome we have studied five kindreds, each with members affected by Pendred syndrome. All families support linkage to the chromosome 7 region, defined by the microsatellite markers D7S501-D7S523. Detailed haplotype analysis refines the Pendred syndrome linkage interval to a region flanked by the marker loci D7S501 and D7S525, separated by a genetic distance estimated to be 2.5 cM. As potential candidate genes have as yet not been mapped to this interval, these data will contribute to a positional cloning approach for the identification of the Pendred syndrome gene.

Adolescent↗
PubMed1997

Craniosynostosis associated with FGFR3 pro250arg mutation results in a range of clinical presentations including unisutural sporadic craniosynostosis.

Several mutations involving the fibroblast growth factor receptor (FGFR) gene family have been identified in association with phenotypically distinct forms of craniosynostosis. One such point mutation, resulting in the substitution of proline by arginine in a critical region of the linker region between the first and second immunoglobulin-like domains, is associated with highly specific phenotypic consequences in that mutation at this point in FGFR1 results in Pfeiffer syndrome and analogous mutation in FGFR2 results in Apert syndrome. We now show that a much more variable clinical presentation accompanies analogous mutation in the FGFR3 gene. Specifically, mental retardation, apparently unrelated to the management of the craniosynostosis, appears to be a variable clinical consequence of this FGFR3 mutation.

Acrocephalosyndactylia↗
PubMed1997

Counselling dilemmas associated with the molecular characterisation of two Angelman syndrome families.

We report the molecular characterisation of two families with Angelman syndrome referred for prenatal diagnosis, in which atypical molecular findings resulted in counselling dilemmas. The first is a familial case of Angelman syndrome in which the two affected children have mutations which affect the imprinting mechanism, as shown by the presence of paternal DNA methylation patterns at D15S63 and SNRPN and biparental inheritance of 15q11-q13 markers. DNA prepared from a 21 week fetal blood sample detected a fetus with normal maternal and paternal DNA methylation patterns at D15S63, but inheritance of the same maternal chromosome 15q11-q13 as the two affected sibs. This is probably a result of germline mosaicism in the mother. The second is a case of Angelman syndrome with an atypical deletion of 15q11-q13, which involves both unusual proximal and distal breakpoints. The deletion was characterised in order to assess the risk of Angelman syndrome in a second pregnancy in the mother of this child.

Angelman Syndrome↗
PubMed1996

Hemihypertrophy, hemimegalencephaly, and polydactyly.

We present clinical and neuropathological details of a patient with hemihypertrophy and hemimegalencephaly who may have Proteus syndrome. The observation of polysyndactyly in the case indicates either that polysyndactyly is a rare manifestation in Proteus syndrome, or that a separate condition, mimicking Proteus syndrome and pursuing a similar clinical course, might exist.

Brain↗
PubMed1996

Analysing human developmental abnormalities.

About one in forty babies is born with a recognisable congenital anomaly at birth. Rapid progress is being made in recognising the genetic contribution to these defects. From over 2000 likely single gene malformation syndromes in humans the gene has been isolated or mapped in about 10%. Despite the availability of animal models, the study of malformations in humans continues to reveal novel genes and unpredicted functions for known genes. The importance of the study of clinical malformations to the understanding of embryological development in humans and other organisms is discussed and reviewed.

Abnormalities, Multiple↗
PubMed1996

What's in a face?

Genetic syndromes causing human facial abnormalities have been extensively studied from the clinical point of view. In these syndromes, distinctive facial features are frequently associated with specific defects of other organ systems, and the genes responsible must all play a significant part in normal development. In this paper genes causing craniofacial abnormalities, that have either been mapped or isolated, are reviewed.

Abnormalities, Multiple↗
PubMed1996

Serpentine fibula syndrome: expansion of the phenotype with three affected siblings.

We describe three siblings, one of whom has serpentine fibula syndrome (SFS) and has many facial and skeletal features in common with two deceased brothers, making it highly likely that they too had the condition. The karyotype of one of the deceased males was 47,XXY. These are the first affected sibs with SFS, and the first affected males. They all have other abnormalities which have not previously been described as part of the condition, namely congenital heart disease, inguinal herniae (two sibs), intestinal malrotation (two sibs) and coloboma (one sib). Facially they resemble the cases described by ter Haar et al. (1983), who also had congenital heart disease and a skeletal dysplasia though did not have the characteristic bowing of the fibulae. There are also features in common with Hadju-Cheney syndrome.

Abnormalities, Multiple↗
PubMed1996

Three sibs with microcephaly, congenital heart disease, lung segmentation defects and unilateral absent kidney: a new recessive multiple congenital anomaly (MCA) syndrome?

We present three sibs with similar dysmorphic features, including brain, heart and lung malformations that have not been reported previously. Cytogenetic studies have failed to demonstrate a chromosomal abnormality. Although parental consanguinity was not present, we suggest that this may constitute a new recessive syndrome.

Abnormalities, Multiple↗
PubMed1996

Midline craniofacial defects and morning glory disc anomaly. A distinct clinical entity.

A case with a severe midline craniofacial defect, comprising a midline cleft lip and palate with a sphenoethmoidal encephalocele, hypertelorism, bilateral dysplastic optic discs and agenesis of the corpus callosum is described. The optic discs are consistent with the spectrum of appearances seen in the Morning Glory Disc Anomaly (MGDA). This anomaly is usually a uniocular problem that may be rarely associated with craniofacial abnormalities. Despite this range of abnormalities this child was developing well with a specific motor delay at the age of eight months. Cases with similar midline craniofacial abnormalities from the literature are reviewed. This condition appears to be a distinct entity within the spectrum of frontonasal dysplasia.

Abnormalities, Multiple↗