Search PubMed⌕ Search

Biomedical subjects

J M Connor

Publications and source records attributed to J M Connor.

At least 145 records · Page 8Linked to original sources
PubMed1987

Efficient isolation of X chromosome-specific single-copy probes from a cosmid library of a human X/hamster hybrid-cell line: mapping of new probes close to the locus for X-linked mental retardation.

We isolated X-chromosomal DNA probes from a cosmid library constructed from a single human X/hamster hybrid-cell line (C12D). One hundred human clones were isolated and used to construct a pool of X-chromosomal DNA. This DNA was digested into 0.15-2-kb fragments and subcloned into plasmids allowing the rapid characterization of new single-copy probes. These were regionally mapped and used for the detection of restriction-site polymorphisms. Together with a series of subcloned probes from individually isolated cosmids, we found seven polymorphic probes among 53 tested. Thirty-one of the probes were physically localized to different regions of the X chromosome. Four polymorphic probes map to Xq27-Xq28: DXS102 (cX38.1), DXS105(cX55.7), DXS107(cpX234), and DXS134(cpX67). These were genetically mapped by multipoint analysis relative to previously characterized loci, a mapping that resulted in the following order: DXYS1, DXS107, DXS51/DXS102, F9, DXS105, Fra-X, F8/DXS52, DXS15, DXS134. The mapping of DXS105 between F9 and Fra-X makes this probe useful for Fra-X analysis. For the linkage between FraX and DXS105, a maximum lod score of 5.01 at 4 cMorgans has been obtained in one large Dutch pedigree.

Animals↗
PubMed1986

Assignment of the gene for dyskeratosis congenita to Xq28.

Dyskeratosis congenita is an X-linked recessive disorder with diagnostic dermatological features, bone marrow hypofunction, and a predisposition to neoplasia in early adult life. Linkage analysis was undertaken in an extensive family with the condition using the Xg blood group and 17 cloned X chromosomal DNA sequences which recognise restriction fragment length polymorphisms (RFLPs). No recombination was observed between the locus for dyskeratosis congenita (DKC) and the RFLPs identified by DXS52 (St14-1) (Zmax = 3.33 at theta max = 0 with 95% confidence limits of 0 to 14cM). Similarly no recombination was observed for the disease locus and F8 (Zmax = 1.23 at theta max = 0) nor for DXS15 (Zmax = 1.62 at theta max = 0), but both of these markers were only informative in part of the family whereas DXS52 was fully informative. DXS52, DXS15, and F8 are known to be tightly linked and have previously been assigned to Xq28. Thus the gene for dyskeratosis congenita can be assigned to Xq28. These DNA sequence polymorphisms will be of clinical value for carrier detection and prenatal diagnosis.

Adolescent↗
PubMed1986

Application of three intragenic DNA polymorphisms for carrier detection in haemophilia B.

In the west of Scotland use of a single intragenic restriction fragment length polymorphism (F9(VIII)/TaqI) allowed definitive genetic counselling for 45% of females at risk of being carriers for haemophilia B. Two further intragenic RFLPs, F9(VIII)/XmnI) and F9(VIII)/DdeI, have been applied to this population and by using all three polymorphisms the carrier status could be determined in 68% of females at risk. Linkage disequilibrium was apparent between these three RFLPs, and in the west of Scotland the single most clinically useful polymorphism was F9(VIII)/TaqI followed by F9(VIII)/DdeI and then F9(VIII)/XmnI. Overall, prenatal diagnosis by DNA analysis could be offered to 31 of 37 (84%) carriers (obligate and detected) in these families.

Cloning, Molecular↗
PubMed1986

Monozygotic twins concordant for congenital short femur.

We report concordant male monozygotic twins with congenital short femur (proximal focal femoral deficiency) and discuss the aetiological implications. Coincidentally, they and their father have benign familial macrocephaly.

Femur↗
PubMed1986

Genetic linkage.

Not all doctors would understand the statement "linkage is now established between a DNA marker and the locus for adult polycystic kidney disease at a recombination fraction of 5%". Yet over the next few years increasing numbers of DNA markers linked to single-gene disorders will become available and clinicians will need to identify patients who could benefit from this knowledge.

Blood Group Antigens↗
PubMed1985

Lethal neonatal chondrodysplasias in the West of Scotland 1970-1983 with a description of a thanatophoric, dysplasialike, autosomal recessive disorder, Glasgow variant.

Complete ascertainment of lethal neonatal short-limb chondrodysplasias was attempted in the West of Scotland for the period 1970-1983. Forty-three cases were identified, representing a minimum incidence of 1 in 8,900. The differential diagnosis included 11 well-delineated skeletal dysplasias, one case of warfarin embryopathy, and one apparently new condition with presumed autosomal recessive inheritance that has radiographic similarities to those of thanatophoric dysplasia (TD). In this series TD had an incidence of 1 in 42,221, which is consistent with new dominant mutation at a rate of 11.8 +/- 4.1 X 10(-6) mutations per gene per generation. Ultrasonic measurement of fetal long bone length was performed in eight subsequent pregnancies at risk. Five unaffected fetuses were predicted correctly and three affected fetuses were detected during the second trimester (one with rhizomelic chondrodysplasia punctata-second trimester prenatal diagnosis not previously reported; one with achondrogenesis type II; and one with the new lethal condition).

Chondrodysplasia Punctata↗
PubMed1985

Non-dermatological complications and genetic aspects of the Rothmund-Thomson syndrome.

We report two new cases of Rothmund-Thomson syndrome which emphasize the less well-known non-dermatological complications, namely: hypodontia, soft tissue contractures, proportionate short stature, hypogonadism, anaemia and osteogenic sarcoma. Genetic analysis of these and previously reported pedigrees supports autosomal recessive inheritance.

Abnormalities, Multiple↗
PubMed1985

Mucosal neuroma syndrome--a phenotype for malignancy.

The mucosal neuroma syndrome is characterised by a typical physical appearance, neuromata on tongue and buccal mucosa, and a high risk of developing medullary thyroid carcinoma and phaeochromocytoma. A case is described and the importance of early recognition for prevention of malignancy is stressed.

Adolescent↗
PubMed1985

Application of an intragenic genomic probe to genetic counselling for haemophilia B in the west of Scotland.

Total ascertainment revealed 28 families with haemophilia B in the west of Scotland (prevalence 1/26 870 males). In 12 of these families more than one person was affected and 26 living obligate carriers were identified and tested. Of these, 42% were heterozygous for a DNA polymorphism recognised by a factor IX genomic probe. No recombination was observed in 11 phase known and four phase unknown informative meioses. Definitive genetic counselling was possible for 14 of 42 females at risk, 11 could not be traced, in 10 the probe was not informative, and in seven paternal absence prevented interpretation. Linkage disequilibrium was apparent for this restriction fragment length polymorphism and haemophilia B in the west of Scotland.

DNA↗
PubMed1985

Pycnodysostosis in a Pakistani family: case presentation and review.

Pycnodysostosis is described for the first time in a Pakistani family. Two cases are presented and are contrasted with cases of osteopetrosis seen in this hospital over a twenty year period. The possibility of confusion with osteopetrosis is indicated and discussed.

Child, Preschool↗
PubMed1984

Inv dup (15) with mental retardation but few dysmorphic features.

We report a Scottish child with inv dup (15) and compare the clinical features with those of previously reported cases. Since the first report by Parker and Alfi in 1972, there have been 44 reports of patients with confirmed or suspected inv dup (15). The extra chromosomal material has been variously described, but in all cases there appears to be an additional G group sized chromosome in which both ends are derived from the short arm, centromere, and proximal long arm of chromosome 15. In most cases there are satellites at both ends of this extra chromosome. We report the first patient from Scotland with similar cytogenetic findings.

Chromosome Aberrations↗