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Biomedical subjects

M Seabright

Publications and source records attributed to M Seabright.

At least 19 recordsLinked to original sources
PubMed1987

Chromosome abnormalities involving band 13q14 in hematologic malignancies.

Fifteen patients with hematologic disorders showed abnormalities involving chromosome band 13q14. Nine patients had an interstitial deletion of this band, similar to that reported in some retinoblastoma tumors and as a constitutional abnormality in a small proportion of cases of familial retinoblastoma. In five patients, band 13q14 was involved in translocations and in one case there was a deletion of one chromosome #13 and a translocation involving the homologous #13. The diagnosis in the majority of our patients (11 of 15) was chronic lymphocytic leukemia. In these patients the abnormalities were detected in cultures stimulated with 4-phorbol 12-myristate 13-acetate (PMA). It is possible that the utilization of this agent is a fundamental requirement for the reliable demonstration of abnormalities involving 13q14 in patients with B-cell malignancies. The incidence of abnormalities involving 13q14 and their significance in the development of neoplasias, other than retino-blastoma, is discussed.

B-Lymphocytes↗
PubMed1986

Chromosome abnormalities in pupils attending ESN/M schools.

One hundred and sixty six children attending educationally subnormal/mild (ESN/M) schools were karyotyped as part of a project investigating the aetiology of mild mental retardation. Nine had significant chromosome abnormalities. Five of six children identified during the survey had no dysmorphic features--47,XXY (two), 48,XXYY, 46,XX 15q-, and 46,XX,t(X;19). One dysmorphic boy had a balanced translocation--46,XY,t(3;15). Three were already known--47,XX+21 (two) and 46,XY, 14q+. We suggest that routine karyotyping of children with mild mental retardation be considered.

Child↗
PubMed1985

The prevalence of translocations in parents of children with regular trisomy 21: a possible interchromosomal effect?

It has been suggested that translocations, and perhaps other chromosome rearrangements, disturb meiotic disjunction of uninvolved chromosome pairs and predispose to trisomic offspring. If so, then one would expect an excess of translocations not involving chromosome 21 among the parents of regular trisomic Down's syndrome patients. Such translocations have been reported, but mostly as anecdotal single case reports or very small series. In an attempt to collect a larger series, a collaborative study of regular Down's syndrome families was made in southern England. This was retrospective, and covered periods of 7 to 10 years since 1970. The number of regular trisomy families investigated was 1454. Only 945 of the 2908 parents were karyotyped, and 10 balanced reciprocal translocations not involving chromosome 21 were identified, together with one Robertsonian (13q14q). Expressing these as percentages of the parents tested (945), prevalences are as follows: reciprocals 1.06%, Robertsonians 0.11%, and all translocations 1.16%. Expressed as percentages of the total parents (2908), tested and untested, the prevalences are 0.34%, 0.03%, and 0.37% respectively. The 'true' prevalences, that is what would have been found had all parents been tested, must lie between these two sets of figures. The prevalence of reciprocal translocations exceeds that found for consecutive banded newborn infants, which is 0.16%, and this excess may reflect a real interchromosomal effect. Robertsonian translocations in the banded newborn series are at a frequency of 0.11%, identical to that found in the tested parents of regular trisomics. Interpretation of these figures is critically dependent upon the real prevalence of translocations among the newborn, estimates of which increase as technical methods are improving.

Adult↗
PubMed1984

Paracentric inversions in man.

We have reviewed 50 cases of paracentric inversions. Of these 34 were familial with 62 phenotypically normal carrier relatives. Twenty of the 50 were discovered fortuitously. There were two reports of children with easily recognised unbalanced karyotypes resulting from a paracentric inversion in one of the parents. The vast majority of paracentric inversions are harmless. The risk of abnormal children for paracentric inversion heterozygotes is low but increases with the finding of recurrent abortions or abnormal children or both in other carriers in the family. We emphasise the need for caution in interpreting the results of antenatal diagnosis because of the variety of unexpected unbalanced chromosome types that can result from a paracentric inversion, and the difficulty in recognising, with confidence, minute differences (for the detection of which very high resolution banding is required) between apparently similar parental and fetal inversions.

Abortion, Habitual↗
PubMed1981

Phenotypically normal individuals with an inversion (X) (p22q13) and the recombinant (X), dup q.

Two families are described in which there is an inv(X) (p22q13) which has been transmitted for three generations. In one family (K482), no recombinants have been recovered and the inversion can be traced to a female born in 1839. In the second family (K491), a recombinant (X), dup q, has been recovered in a normal fertile woman. In both families the inverted X appears to be carrying the Xg allele. Despite extensive family studies no common ancestor has been found for the two families. The pattern of DNA synthesis has been studied in those individuals who are karyotypically 46,X,inv(X) (p22q13) and 46,X,rec(X)dup 1, inv(X) (p22q13); the selection of the abnormal as the late synthesizing X chromosome is random in the former and total in the latter. In some cells the two long arms of the recombinant X chromosome showed asynchrony of DNA replication.

Adult↗
PubMed1980

Pericentric inversion (13) with two different recombinants in the same family.

A family is described in which a pericentric inversion (13) was discovered in the father after the birth of an abnormal baby. In a further pregnancy amniocentesis was carried out. The fetal karyotype showed a rec(13)dup p,inv(13)(p11q22). The fetus's abnormalities were similar to those observed in the first child. Family studies showed that a first cousin, mentally retarded, had a rec(13)dup q,inv(13)(p11q22) karyotype. In this family, the risk of occurrence of a recombinant in offspring of an inversion carrier could be as high as 40%.

Abnormalities, Multiple↗
PubMed1980

A familial polymorphic variant of chromosome 5.

Two male fetuses and their mothers, referred for amniocentesis because of high levels of AFP in their blood, were found to carry an anomalous chromosome 5 with a large heterochromatic segment in the long arm. One of the fetuses had an additional ring chromosome.

Adult↗
PubMed1978

Interstitial deletion of chromosome 7 detected in three unrelated patients.

Chromosome studies were carried out on three patients for the following reasons: (1) growth retardation and mental subnormality in a boy; (2) marked developmental delay in a female infant; (3) routine check on a man whose wife had a stillborn with congenital anomalies. An interstitial deletion at 7q11::7q21 was observed in all three cases.

Abnormalities, Multiple↗
PubMed1978

Rearrangements involving four chromosomes in a child with congenital abnormalities.

This report describes a complex structural rearrangement between chromosomes X and 1 and a 7;13 translocation (together involving six break points) in a child with multiple congenital defects. Both parents showed a normal chromosome complement, suggesting that the changes may have originated either in a gametic nucleus or at a very early stage of zygotic development.

Abnormalities, Multiple↗
PubMed1977

Two cases of trisomy 21 and one XXY case with atypical clinical features.

Three patients with mental retardation and multiple congenital abnormalities are described. Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype.

Abnormalities, Multiple↗