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Biomedical subjects

E C Jenkins

Publications and source records attributed to E C Jenkins.

At least 55 records · Page 3Linked to original sources
PubMed1989

Chromosomal abnormalities in amniotic fluid cell cultures: a comparison of apparent pseudomosaicism in Chang and RPMI-1640 media.

The finding of chromosome mosaicism is one of the most difficult problems in fetal chromosome analysis. Whether the finding indicates true mosaicism or pseudomosaicism must be investigated. Studies detailing the incidence of true mosaicism and pseudomosaicism have been reported (Hsu & Perlis 1984, Bui et al. 1984, Worton & Stern 1984) but do not correlate pseudomosaicism with any particular type of culture media. Benn & Hsu (1985) compared cell growth and chromosome abnormalities in amniotic fluid cell cultures grown in Chang medium and RPMI-1640 medium and found no statistically significant difference in the rate of abnormalities in the two media. We have previously shown that Chang medium exhibited more abnormalities which were not verified in second and third cultures (Masia et al. 1986). In the current study we examined 212 cases grown in both Chang and RPMI-1640 media, and compared apparent single and multiple cell pseudomosaic abnormalities to medium type. The number of observed abnormalities was 22, occurring in 19 of the cases studied. Apparent pseudomosaic chromosome anomalies were observed in 18 Chang cultures and in 4 RPMI-1640 cultures. Statistical analysis found significant correlation between medium type and the degree of observed pseudomosaic cells. We conclude that the rate at which pseudomosaic cells are observed is partly a function of medium type, and in our laboratory Chang medium caused apparent pseudomosaicism at a greater level than RPMI-1640 medium.

Amniotic Fluid↗
PubMed1989

Parent-child dyadic gaze patterns in fragile X males and in non-fragile X males with autistic disorder.

Parent-child dyadic gaze patterns were examined in fragile X [fra(X)] males and in non-fra(X) autistic males across three age groups--early childhood, middle childhood and adolescence. Absolute probabilities of social gaze did not significantly differ across diagnostic groups. Event lag sequential analyses indicated that fra(X) males were sensitive to social gaze initiation by their parents but found eye contact aversive. Non-fra(X) autistic males, by contrast, were insensitive to parent-initiated social gaze, and did not find eye contact aversive. Implications for research on the social characteristics of fra(X) and autistic children are discussed.

Adolescent↗
PubMed1989

Beta-amyloid protein probe hybridized to chromosome 9 in 3 Alzheimer disease individuals.

We have reported recently the sublocalization of an Alzheimer Disease-associated gene that encodes for cerebrovascular beta-amyloid protein (BAP). Its locus appears to be at or proximal to band 21q2105 through band 21q11.1. We have also observed hybridization to chromosome 20 in normal and Down syndrome individuals using the single-stranded form of the probe. Further, we have found that BAP hybridizes to chromosome 9 in lymphoblastoid cells from three individuals from two families with familial Alzheimer Disease (AD). We have now obtained additional data which shows significant hybridization to chromosomes 9,20 and 21 for two normal control individuals, a Down syndrome (DS) individual and three AD individuals. When the normal and Down Syndrome individuals were compared to the group of individuals with AD, significant hybridization to chromosome 9 occurred in the Alzheimer group only (p less than .05). Almost half of the silver grains on chromosome 9 in the three AD individuals were localized to the distal area of the long arm. Whether these observations demonstrate an apparent genetic marker in these three individuals with familial AD, or whether our observations have identified a marker for both familial and sporadic AD will be determined by further studies.

Alzheimer Disease↗
PubMed1989

Clinical features of a neuropathologically verified familial Alzheimer's cohort with onset in the fourth decade: comparison with senile onset Alzheimer's disease and etiopathogenic implications.

Clinical and pathologic features of a family with early onset, autosomal dominant, familial Alzheimer's disease (AD) are compared and contrasted with senile onset dementia of the Alzheimer type. Late onset AD has previously been observed to have a characteristic progression and clinical course. A previously unreported pedigree, with two siblings and their father affected, of early clinical onset is presented. Molecular genetic study of this family using in situ chromosome hybridization showed an apparent marker on chromosome 9. This early onset form of AD is observed to be clinically consistent with the common late onset form of AD, but follows a more rapid course. An etiopathogenic model explaining the early onset, and other forms of AD is presented.

Adult↗
PubMed1988

Fine mapping of an Alzheimer disease-associated gene encoding beta-amyloid protein.

We have sublocalized an Alzheimer Disease-associated gene, which encodes for cerebrovascular beta-amyloid protein, to the region from the centromere through the proximal half of band 21q21 using both somatic cell and in situ mapping techniques. In addition we found repeatedly significant but weaker hybridization of the beta-amyloid protein probe to the short arm of chromosome 20. 794 cells were analyzed from whole blood, lymphoblastoid and skin cultures. The latter two types of cultures had parts of the 21st chromosome translocated to other chromosomes facilitating sublocalization.

Alzheimer Disease↗
PubMed1988

Multilocus analysis of the fragile X syndrome.

A multilocus analysis of the fragile X (fra(X] syndrome was conducted with 147 families. Two proximal loci, DXS51 and F9, and two distal loci, DXS52 and DXS15, were studied. Overall, the best multipoint distances were found to be DXS51-F9, 6.9%, F9-fra(X), 22.4%; fra(X)-DXS52, 12.7%; DXS52-DXS15, 2.2%. These distances can be used for multipoint mapping of new probes, carrier testing and counseling of fra(X) families. Consistent with several previous studies, the families as a whole showed genetic heterogeneity for linkage between F9 and fra(X).

Chromosome Mapping↗
PubMed1988

Social gaze, social avoidance, and repetitive behavior in fragile X males: a controlled study.

Preference for social gaze as well as the percentage occurrence of social gaze, nonverbal social avoidance, and nonverbal repetitive behaviors were examined in autistic and nonautistic prepubertal males with the fragile X syndrome (fra[X]) during social interaction with a parent or stranger. Comparison groups were nonhandicapped, Down syndrome, atypical pervasive developmental disorder, and autistic males. The subjects with fra(X) and the nonhandicapped and Down syndrome control subjects discriminated parent from stranger as evidenced by their avoidance behavior. The overall percentage of avoidance was higher, however, for both parent and stranger, among the males with fra(X). Autistic and atypical groups without fra(X) failed to discriminate parent from stranger in their avoidance behavior. Possible explanations for these group differences in terms of language level or degree of language demand were ruled out. Implications for research concerning the relations among fra(X), autism, and mental retardation were discussed.

Autistic Disorder↗
PubMed1987

Further evidence for genetic heterogeneity in the fragile X syndrome.

The X-linked fragile X [fra(X)] syndrome, associated with a fragile site at Xq27.3, is the most common Mendelian inherited form of mental deficiency. Approximately 1 in 1060 males and 1 in 677 females carry the fra(X) chromosome. However, diagnosis of carrier status can be difficult since about 20% of males and 44% of females are nonpenetrant for mental impairment and/or expression of fra(X). We analyzed DNA from 327 individuals in 23 families segregating fra(X) for linkage to three flanking polymorphic probes: 52A, F9, and ST14. This allowed probable nonpenetrant, transmitting males and carrier females to be identified. A combined linkage analysis was conducted using these families and published probe information on F9 in 27 other families, 52A in six families, and ST14 in five families. The two-point recombination fraction for 52A-F9 was 0.13 (90% confidence interval, 0.10-0.16), for F9-fra(X) was 0.21 (0.17-0.24), and for fra(X)-ST14 was 0.12 (0.07-0.17). Tight linkage between F9 and fra(X) was observed in some families; in others loose linkage was seen suggesting genetic linkage heterogeneity. Risk analysis of carrier status using flanking DNA probes showed that probable nonpenetrant transmitting males were included in families showing both tight and loose linkage. Thus, in contrast to our previous conclusions, it appears that the presence or absence of nonpenetrant, transmitting males in a family is not an indicator of heterogeneity. To determine if heterogeneity was present, we employed the admixture test. Evidence for linkage heterogeneity between F9 and fra(X) was found, significant at P less than 0.0005. Nonsignificant heterogeneity was seen for 52A-F9 linkage. No heterogeneity was found for fra(X)-ST14. The frequency of fra(X) expression was significantly lower in families with tight F9-fra(X) linkage than in families with loose linkage. Cognition appeared to relate to linkage type: affected males in tight linkage families had higher IQs than those in loose linkage families. These findings of genetic heterogeneity can account in part for the high prevalence and apparent high new mutation rate of fra(X). They will affect genetic counseling using RFLPs. An understanding of the basis for genetic heterogeneity in fra(X) will help to clarify the nature of the unusual pattern of inheritance seen in this syndrome.

Fragile X Syndrome↗
PubMed1987

Genetics and expression of the fragile X syndrome.

The discovery of the Fragile X (fra(X] syndrome represents a major advance in our understanding of mild mental retardation. This X-linked syndrome is the most common hereditary form of mental retardation. Recent estimates find that approximately 1/981 males and 1/677 females carry the fra(X) chromosome. The majority of affected males are moderate to severely retarded, but about 20% are mildly retarded and about 5% are borderline. Approximately 20% of males who inherit the fra(X) chromosome are termed non-penetrant; they do not express it cytogenetically and are of normal intellect. About 1/3 of carrier females show mental impairment and about 10% are mildly retarded. We have found evidence for genetic heterogeneity based on linkage analysis to flanking DNA probes. Some large families show tight linkage between fra(X) and the flanking probe F9, while others show loose linkage. Preliminary findings indicate the linkage heterogeneity may also be related to cognition: affected males in tightly linked families tended to be mildly retarded.

Cognition Disorders↗
PubMed1987

Assignment of proteins to human chromosome 21 using two-dimensional gel electrophoresis and somatic cell genetics: an approach to the study of Down syndrome.

A mouse hybrid cell line (WA17d) was derived which contained multiple copies of human chromosome 21 and no other human chromosome. Cell extracts of this line were prepared and subjected to two-dimensional gel electrophoresis. Several proteins were identified whose synthesis was altered by the presence of chromosome 21 and 6 proteins were identified as being specific to this human chromosome. These gene products might be involved in the pathogenesis of Down syndrome and be related to the neurologic defects and premature aging seen in this common chromosome abnormality.

Aging↗
PubMed1986

Localization of a human gene homologous to the PrP gene on the p arm of chromosome 20 and detection of PrP-related antigens in normal human brain.

Infectious fractions prepared from scrapie-infected hamster brains contain a protein, PrP 27-30, which shares antigenic determinants with polypeptides found in similarly prepared fractions from patients with Creutzfeldt-Jakob disease. cDNA sequences encoding the hamster PrP 27-30 identified homologous sequences in the human genome as well as in normal human brain mRNA preparations. Antibodies raised against the mouse PrP's identified antigenically related peptides in both normal hamster and human brain as well as in scrapie-infected hamster brain and CJD-affected human brain. By using in situ hybridization we localized the homologous human genomic sequences on the short arm of chromosome 20. Our results indicate that the reportedly unique proteins detected in human CJD preparations derive from normal human gene products.

Animals↗
PubMed1986

A profile of cognitive deficit in females from fragile X families.

Fragile X, a recently discovered X-linked syndrome, is usually associated with mental retardation in affected males. Less consistent findings have been described for females. neuropsychological evaluation of seven nonretarded females from fragile X families suggested a characteristic profile: on Wechsler IQ tests, a positive Verbal-Performance score difference and lower subtest scaled scores on Arithmetic, Digit Span, Block Design, and Object Assembly; on the Wide Range Achievement Test, a lower score on Arithmetic than on Reading or Spelling; and on the Benton Visual Retention Test, defective recall. These results suggest the existence of X-linked learning disability in females.

Achievement↗