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Biomedical subjects

B Le Marec

Publications and source records attributed to B Le Marec.

At least 73 records · Page 4Linked to original sources
PubMed1986

[Genetic counseling in cancerology].

The authors have studied the different situations that prompt a request for genetic counseling if different members of the same family suffer from cancer. Six possibilities are considered: the cancer concerned is a genetic disease per se (e.g. retinoblastoma, thyroid cancer with amyloid stroma); the genetic disease is often complicated with cancer (e.g. intestinal polyposis); the genetic disease is occasionally complicated with cancer (e.g. neurofibromatosis); cancer is part and parcel of the genetic disease (e.g. chromosomal abnormalities); in addition, there are two special situations: "cancer-prone families" and families who request genetic counseling after one single case (e.g. cancer of leukaemia in a child).

Genetic Counseling↗
PubMed1986

De novo DNA microdeletion in a girl with Turner syndrome and Duchenne muscular dystrophy.

The single X chromosome of a girl with Turner syndrome (45,X) and typical Duchenne muscular dystrophy was investigated at the chromosomal and DNA levels. No visible abnormality of the residual X chromosome was found upon high-resolution R-banding. The DNA was analysed by Southern blotting and hybridization with seven cloned probes mapping in the Xp21 region where the Duchenne locus is thought to be located. A molecular deletion was detected with probes pERT 87.1, pERT 87.8, and pERT 87.15. The other probes (754, C7, 99.6, and RC8) gave a normal signal. The DNA alleles seen in the two parents indicated that the deletion found in the propositus had occurred de novo on a maternal X chromosome.

Adolescent↗
PubMed1986

46,XX,t(15;21)/47,XX,15p-,+21 mosaicism in a child with Down's syndrome.

We report here the first case of a mosaic Down's syndrome in which both clones are trisomic for chromosome 21, one of them (90%) by a Robertsonian translocation (15;21) appearing de novo, and the other (10%) by an additional chromosome 21. Three hypotheses can explain the appearance of such a mosaic: that of a chimera formed by the fusion of two trisomy 21 zygotes, one of which had a Robertsonian translocation, the other an additional trisomy 21 zygote; that of a fusion between a chromosome 15 and a chromosome 21 in one of the early segmentation blastomeres of a trisomy 21 zygote; the more probable hypothesis of the occurrence of a fission at the break-attachment point of a Robertsonian translocation (15;21) in one of the cells arising from the early postzygotic divisions of a zygote which was a trisomy 21 by Robertsonian translocation (15;21).

Chromosomes, Human, Pair 15↗
PubMed1986

Structural genes of coagulation factors VII and X located on 13q34.

From 7 cases of abnormalities involving chromosome 13, the structural gene(s) coding for coagulation factors VII and X were located in the region 13q34-13qter. Gene-dosage effects for these coagulation factors seem to act in both directions, causing a decrease when there is monosomy of segment 13q34, but also, as has not been demonstrated before, an increase when there is trisomy of this same segment.

Adolescent↗
PubMed1986

Meiotic behaviour of familial pericentric inversions of chromosomes 1 and 9.

Pachytene analysis was carried out in two infertile brothers, one heterozygous for two pericentric inversions of chromosomes 1 and 9, the second heterozygous for the pericentric inversion of chromosome 1. The synaptic behaviour of the bivalent 1 inversion was the most informative. Analysis of the chromomere pattern combined with centromeric heterochromatin staining and synaptonemal complexes visualization allowed precise description of synaptic initiation and extension leading to the homosynapsed loop. Heterosynapsis following alignment of the inverted segments was demonstrated. Non-homologous synapsed bivalents had the morphological aspects of straight bivalents with two distant blocks of centromeric heterochromatin. The possible sterilizing effect caused by the autosomal inversion is discussed.

Adult↗
PubMed1986

[Evaluation of the incidence of anencephaly and spina bifida in Brittany (1975-1984)].

Brittany is celtic, like Ireland and Wales where the incidence of neural tube defects is raised. We searched the hospital files in Brittany for all live and still births, and terminations of pregnancy after prenatal diagnosis for the years 1975-1984. 225 cases of spina bifida and 210 cases of anencephaly were identified; giving an incidence of 0.60 per 1000 births for spina bifida and 0.56 per 1000 births for anencephaly. No seasonality was found for both malformations. Analysis of the sex ratio for anencephaly indicated significantly higher proportion of females to males. Maternal age in the affected group was similar to the normal population. Casual heterogeneity among neural tube defects patients was presumed because 14% of our cases had other congenital anomalies.

Abnormalities, Multiple↗
PubMed1986

[Anencephaly and diprosopy: 2 cases].

We have seen two cases of diprosopy associated with anencephaly in Brittany between 1975 and 1984. Diprosopy is a partial or total duplication of the face. It consists of the phenomenon of late division in the embryo of the cephalic portion of the neural plate between the 16th and the 18th days. This gives rise to an incomplete type of monozygotic twinning or a conjoint twin. There are several different forms of the organs that are duplicated. We have seen a case of diprosopos distomos dirhinos diophthalmos and a case of disprosopos distomos dirhinos triophthalmos. These two cases were associated with anencephaly, the second also having a spina bifida and a diaphragmatic hernia. One can explain the incidence of anencephalies in cases of diprosopies by the desturbance created by the latter on the embryological events that succeed it. The delay in nerve formation makes it impossible for the neural tube to close completely, and this is why sometimes the anencephaly is associated with spina bifida. In more general terms one can postulate that all conjoint twins that are, of course, monozygotic and monochorial can interfere with early enbryological development and increase the risks of failure of the neural tube to close.

Abnormalities, Severe Teratoid↗
PubMed1985

Ultrasonographic anatomy and physiology of the fetal kidney.

The aim of this work was to demonstrate the impact of ultrasonography in utero to gain a better understanding of the anatomy, growth, anatomical variations and function of the fetal kidney and urinary tract. Three main topics are discussed in this paper based on the authors' personal experience and data from the literature: 1) the technique of ultrasonography in utero, including the main difficulties encountered and limitations of this technique; 2) ultrasonographic study of the morphology, growth and anatomical variations of the fetal kidney. The length of the fetal kidney was found to be the most significant parameter for assessment of its growth. At term, the kidney measures slightly more than 4 cm in length, while the renal pelvis is usually no more than 10 mm thick; 3) current knowledge of the physiology of the fetal urinary apparatus especially the kidney. Excretory function of the kidney begins in the third month of gestation and its main role involves the regulation of the amniotic fluid.

Embryonic and Fetal Development↗
PubMed1985

[Prenatal diagnosis of abnormalities of the neuroectodermal tube. Limitations of the assay of amniotic alpha fetoprotein and acetylcholinesterase and value of the qualitative study of cholinesterases. Apropos of 6 cases of anencephaly].

Measurement of amniotic fluid alpha-foetoprotein and acetylcholinesterase for the detection of neural tube defects has been used in 285 normal or neural tube defects affected pregnancies: 18 false positive results (with non neural tube defects fetal malformations) have been reported. A qualitative polyacrylamide gel electrophoresis technique has been used to identify the acetylcholinesterase isoenzyme derived from foetal cerebrospinal fluid. Results illustrate the value of amniotic fluid acetylcholinesterase electrophoresis. Amniotic cholinesterase presence may serve as a valuable marker for the detection of neural tube defects.

Acetylcholinesterase↗