PubMed Health⌕ Search

Biomedical subjects

M E Pembrey

Publications and source records attributed to M E Pembrey.

At least 19 recordsLinked to original sources
PubMed1992

Diabetes mellitus associated with a pathogenic point mutation in mitochondrial DNA.

Family studies of diabetes mellitus (DM) show that patients are more likely to have affected mothers than affected fathers. Since the inheritance of mitochondrial (mtDNA), unlike nuclear DNA, is exclusively maternal, could it be that defect(s) in mtDNA account for some cases of DM? Such defects have been associated with rare neurological syndromes, in some of which DM has been an accompanying feature. We have looked for glucose intolerance and for a previously known point mutation of mtDNA in a family, some of whose members have a multisystem disorder with DM but not neurological involvement. DNA samples were obtained from fourteen family members. The point mutation (affecting position 3243 in the tRNA leucine mitochondrial gene) was found in all three diabetic patients and post mortem tissues in the proband; it was also found in seven offspring of female patients. It was not found in the two children of the male proband. The contribution of this mutation to DM in general is not known but clinicians ought to be aware of the possibility, especially in families with multisystem disease and maternal transmission.

Adult↗
PubMed1992

Further evidence for dominant inheritance at the chromosome 15q11-13 locus in familial Angelman syndrome.

Eleven patients with Angelman syndrome (AS) and their parents from 5 families have been studied with high resolution chromosome analysis and molecular probes from region 15q11-13 in an attempt to elucidate the mode of inheritance in familial AS. No deletions were detected. All families were informative with a combination of different short arm cytogenetic markers. All sets of sibs inherited the same maternal chromosome 15, but in 3 families sibs inherited different paternal 15s. Analysis of 6 polymorphic DNA markers supported the conclusion that AS sibs inherit the same maternal 15, but often different paternal 15s. These data make autosomal recessive inheritance at a 15q11-13 locus very unlikely and support the hypothesis that familial AS is due to maternal transmission of a mutation within 15q11-13.

Angelman Syndrome↗
PubMed1992

Maternal origin of deletion 15q11-13 in 25/25 cases of Angelman syndrome.

About half of the cases of Angelman syndrome arise from deletions of chromosome band 15q12. In 25 cases we have been able to determine the parental origin of the deletion and, in line with other reported cases, we have found the deletion to be of maternal origin. There were no exceptions. The parental origin was determined using cytogenetic markers in 13 of the cases, in nine by using the pattern of inheritance of restriction fragment length polymorphisms, and in three using both techniques.

Abnormalities, Multiple↗
PubMed1992

Angelman syndrome with a chromosomal inversion 15 inv(p11q13) accompanied by a deletion in 15q11q13.

A family is described in which an inversion of chromosome 15, 15 inv(p11q13), is segregating. All family members are healthy except the proband who is a 10 year old boy with Angelman syndrome. Although the chromosomal inversion has been passed from the grandfather to both his son and his daughter with no ill effect, passage from daughter to grandson has resulted in a deletion of chromosome 15 material which is presumed to be the cause of Angelman syndrome in this boy. The probabilities of an inversion of this type being instrumental in causing the syndrome are discussed.

Angelman Syndrome↗
PubMed1992

Angelman syndrome.

Explore the source record for details and available documents.

Intellectual Disability↗
PubMed1992

Clinical and genetic heterogeneity in X-linked deafness.

The use of molecular techniques in respect of the rare X-linked non-syndromic form of genetic deafness demonstrates that this is a genetically heterogeneous disorder, with evidence for at least two separate gene loci on the X chromosome. Audiological heterogeneity in this condition is emphasized by the observation of both mixed deafness and sensorineural deafness in pedigrees showing evidence for linkage to Xq13-q21. The importance and shortcomings of the audiogram in assessing females who are known gene carriers is discussed.

Adolescent↗
PubMed1992

Microdeletions in patients with gusher-associated, X-linked mixed deafness (DFN3).

Employing various probes from the proximal part of the Xq21 region, which is known to harbor the DFN3 gene, we have investigated 13 unrelated male probands with X-linked deafness, to detect possible deletions. For two of these patients, microdeletions could be detected by using probe pHU16 (DXS26). One of these deletions also encompasses locus DXS169, indicating that it extends farther toward the centromere. The presence of normal hybridization patterns in the DNA of 25 unrelated control males suggests that these deletions are the primary cause of progressive mixed deafness in these patients. If so, their molecular characterization may pave the way for the identification and isolation of the corresponding gene.

Chromosome Deletion↗
PubMed1991

Uniparental paternal disomy in Angelman's syndrome.

Angelman's syndrome and Prader-Willi syndrome are both causes of mental retardation with recognisable, but quite different, clinical phenotypes. Both are associated with deletions of chromosome 15q11-13, of maternal origin in Angelman's and paternal in Prader-Willi. Prader-Willi can arise by inheritance of two chromosomes 15 from the mother and none from the father (uniparental maternal disomy). In 2 patients with Angelman's syndrome we found evidence of uniparental paternal disomy. The phenotypic effects of maternal and paternal disomy of chromosome 15 are very different and inheritance of two normal 15s from one parent does not lead to normal development--strong evidence in man for genomic imprinting, in which the same gene has different effects dependent upon its parental origin.

Alleles↗
PubMed1991

A multipedigree linkage study of X-linked deafness: linkage to Xq13-q21 and evidence for genetic heterogeneity.

A locus for X-linked nonsyndromic deafness has previously been allocated to the Xq13-q21 region based on linkage studies in two separate pedigrees. This has been substantiated by the observation of deafness as a clinical feature of male patients with cytogenetically detectable deletions across this region. The question of a second locus for deafness in this chromosomal region has been raised by the audiologically distinct nature of the deafness in some of the deleted patients compared to that observed in those patients upon whom the linkage data are based. We have performed detailed clinical evaluation and linkage studies on seven pedigrees with nonsyndromic X-linked deafness and conclude that there is evidence for at least two loci for this form of deafness, including one in the Xq13-q21 region. We have observed different radiological features among the pedigrees which map to Xq13-q21, suggesting that even among these pedigrees the deafness is due to different pathological processes. Given these findings, we suggest that the classification of nonsyndromic X-linked deafness based solely on audiological criteria may need to be reviewed.

Chromosome Mapping↗
PubMed1991

Nesidioblastosis: evidence for autosomal recessive inheritance.

The risk of recurrence of nesidioblastosis is unclear. Thirty patients from 28 families were studied; the marriages were consanguineous in five families. The ratio of subsequent affected to unaffected siblings was similar to that of an autosomal recessive condition and the sex ratio was close to 1.

Female↗
PubMed1991

X linked alpha thalassaemia/mental retardation: spectrum of clinical features in three related males.

We describe three males (two brothers and a cousin) who have the X linked alpha thalassaemia/mental retardation (ATR-X) syndrome. The diagnosis, originally suspected in the brothers because of similarity in dysmorphic features to previous cases, was confirmed haematologically in the surviving brother. The cousin has less typical dysmorphism and a virtually normal routine blood count, but haemoglobin H inclusions were found in his red blood cells showing that he has the same condition. This report expands the clinical phenotype of the ATR-X syndrome and emphasises that a normal blood count does not exclude the diagnosis.

Adolescent↗
PubMed1991

Microtia and short stature: a new syndrome.

Bilateral microtia, absent patellae, short stature, poor weight gain, and characteristic facial features are described in two female sibs. Other skeletal anomalies included complete habitual dislocation of the elbow, slender ribs and long bones, abnormal modelling of the glenoid fossae with hooked clavicles, and clinodactyly. Bone age was significantly delayed and there was flattening of the epiphyses. This unusual combination of features has many similarities to the syndrome described by Hurst et al.

Abnormalities, Multiple↗
PubMed1978

Fetal haemoglobin production and the sickle gene in the oases of Eastern Saudi Arabia.

Fetal haemoglobin (HbF) levels have been measured in 137 normal (AA) subjects, 109 with the sickle-cell trait (AS) and 237 with sickle-cell anaemia (SS) from the oasis population of Eastern Saudi Arabia. In addition the proportion of F-cells has been estimated in 71 AA, 51 AS and 34 SS subjects. The mean HbF% (and the range of F-cells %) were: AA 0.77 (0.3--18), AS 1.38 (2.3--43) and SS 25.56 (33--98). The distribution of Hb F was always heterocellular. The influence of pregnancy accounts for most of the excess female subjects with sickle-cell trait showing raised Hb F and F-cells. Whilst the normal Arabs and those with sickle-cell trait did not differ from comparable groups of American blacks, both the % Hb F and % F-cells in Saudi Arabian patients with sickle-cell anaemia were much higher than in Blacks. The high Hb F levels in individuals with sickle-cell anaemia are not due to coexistent glucose-6-phosphate dehydrogenase deficiency or alpha-thalassaemia trait, and the Hb F level showed an inverse correlation with the degree of haemolysis. These findings indicate that the unusually elevated levels of Hb F are not due to an associated high frequency of a gene for hetero-cellular hereditary persistence of fetal haemoglobin in the oasis population, but rather from a genetically determined absolute increase in Hb F production related in some way to the SS genotype.

Adolescent↗