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Biomedical subjects

D Riordan

Publications and source records attributed to D Riordan.

16 recordsLinked to original sources
PubMed2002

Identification of a dup(5)(p15.3) by multicolor banding.

A 7-year-old female was referred to the Genetics Clinic because of developmental delay and attentional difficulty. The patient was adopted and there was a nonspecific prenatal history of drug and alcohol abuse. The patient had clinical signs that were not compatible with typical fetal alcohol syndrome (FAS), although there was a history of alcohol exposure in utero, neurodevelopmental difficulties with learning and behavioral problems, and mild dysmorphisms. Cytogenetic analysis revealed an unbalanced female karyotype with a dup(5) containing additional chromosome 5 material at band 5p15.3. The dup(5) showed normal copy number of the cri-du-chat region on 5p15.2 using locus-specific probes D5S721 and D5S23. Multicolor banding of chromosome 5 (MetaSystems) using partial chromosome paint (pcp) probes showed a duplication of band 5p15.3. The karyotype of the patient was therefore interpreted as follows: 46,XX,add(5)mat.ish dup(5)(p15.3)(wcp5 +, D5S271 +, D5S23 +, C84C11/T3 + +, pcp5p15.3 + +). The patient's biological mother and maternal half-brother were found to carry the identical chromosome duplication. The clinical phenotype of the biological mother is complicated by a difficult lifestyle but there were apparent learning and behavioral difficulties at school. The half-brother is nondysmorphic and presents with learning problems and attention deficit disorder (ADD). His physical examination was normal. To the best of our knowledge, this is the first report of a limited duplication of 5p15.3. The clinical significance of the dup(5)(p15.3) is still uncertain but may be the basis for learning and attention difficulties.

Abnormalities, Multiple↗
PubMed2002

Cryptic chromosome rearrangements detected by subtelomere assay in patients with mental retardation and dysmorphic features.

The regions near telomeres of human chromosomes are gene rich. Chromosome subtelomere rearrangements occur with a frequency of 7-10% in children with mild-to-moderate mental retardation (MR) and approximately 50% of cases are familial. Clinical investigation of subtelomere rearrangements is now prompted by fluorescence in situ hybridization (FISH) analysis using specific DNA probes from all relevant chromosome ends. In our study, 40 children were selected for subtelomere assay using either the Chromophore Multiprobe-T Cytocell device or the VYSIS TelVision probes. Inclusion criteria were: developmental delay or MR; a normal 550 G-band karyotype; FRAXA negative; and at least one other clinical criterion. Exclusion criteria included an identified genetic or environmental diagnosis. Of the 40 patients analysed, four (10%) were found to have subtelomere rearrangements. Three of 40 (7.5%) were found to have an unbalanced subtelomere rearrangement and one of 40 (2.5%) was found to have an apparently normal variant subtelomere deletion. The first of the three with an unbalanced karyotype was the result of a familial translocation, the second was a de novo finding, and the origin of the third could not be determined. The subtelomere FISH assay detected almost twice the frequency of unbalanced karyotypes as those detected by 550 G-banding in our cytogenetics laboratory (4.7%). In addition, subtelomere screening was eight times more likely than fragile X screening in our DNA laboratory (1%) to detect genetic abnormalities in mentally handicapped individuals. Our findings support the view that screening for subtelomere rearrangements has a greater positive yield than other commonly used genetic investigations and, if cost and resources permit, should be the next diagnostic test of choice in a child with unexplained MR/dysmorphisms and a normal 550 G-band karyotype.

Abnormalities, Multiple↗
PubMed2001

Mosaic trisomy of a small r(1) with an abnormal phenotype.

Cytogenetic studies of a mildly dysmorphic 10-year-old male with mild developmental delay and learning difficulties revealed mosaicism for a supernumerary ring chromosome in approximately half of the cells. The karyotype of this patient was established as 47,XY,+r[15]/46,XY[15].ish r(1)(D1Z7+,wcp1-). Although the presence of euchromatic material was shown by C banding, the lack of hybridization with the whole chromosome paint 1 (wcp1) probe suggests that few unique sequences are contained in the ring and that these sequences likely explain the child's dysmorphic features and developmental delay. A review of the literature, including the present case, suggests that the significance of euchromatin in supernumerary r(1) as determined by both C banding and fluorescence in situ hybridization (FISH) with chromosome 1 painting probes can be used as a prognostic indicator for potential severity of the clinical phenotype.

Child↗
PubMed1999

Mother-infant interaction in post-partum women with schizophrenia and affective disorders.

BACKGROUND: Psychiatric mother and baby units are increasingly asked to assess parenting in people with severe mental illness, particularly schizophrenia, but little research evidence exists on which to base assessments. METHOD: Mother-infant interaction was assessed in 26 women who had recovered from the acute phase of severe post-partum mental disorder, a validated rating scale based on direct observation was used. RESULTS: Women with schizophrenia showed greater interaction deficits than those with affective disorders, being more remote, insensitive, intrusive and self-absorbed. The 4-month-old infants of women with schizophrenia were more avoidant, and the overall quality of mother-infant interaction in schizophrenia was poorer. CONCLUSION: The long-term significance of these preliminary findings is not known but they raise concerns about the parenting capacity of women with schizophrenia and suggest the need for an intervention to improve parenting skills in this group.

Adult↗
PubMed1998

Functional mosaic trisomy of 1q12-->1q21 resulting from X-autosome insertion translocation with random inactivation.

Cytogenetic studies of a 16-year-old female with behaviour and learning problems revealed that one X chromosome had additional material inserted at Xq21. Fluorescence in situ hybridization (FISH) analysis showed that the inserted segment contained heterochromatin and adjacent euchromatin of chromosome 1 origin. The karyotype of this patient was established as: 46,X,der(X)ins(X;?)(q21;?).ish der(X) ins(X;1)(q21;q12q21)(wcp1+). Chromosome replication studies demonstrated a random pattern of X inactivation, suggesting that the inserted material may be too 'small' to skew lyonization. The consequences of this abnormal X chromosome in relation to the clinical phenotype are discussed.

Adolescent↗
PubMed1998

The evaluation of 15q proximal duplications by FISH.

Six patients from the clinical cytogenetics laboratory identified as having the normal variant dup(15)(q12) were further evaluated using fluorescence in situ hybridization (FISH). The purpose of this study was to ascertain whether any of the Prader Willi Angelman Chromosome Region (PWCR and ANCR, respectively) loci were duplicated in these patients. The results indicated that the patients could be categorized into two groups. The first group showed no duplication of the PWCR ANCR loci and appeared to belong to the dup(15)(q12) class which is phenotypically silent and is therefore called the normal variant. The second group also showed no duplication of the PWCR/ANCR loci. but had a large alpha satellite variant with D15Z. It is hypothesized that these patients do not have a duplication of 15q12 but rather a centromeric variant which mimics the dup(15)(q12). This study confirms the importance of evaluating apparent variations in the proximal region of chromosome 15 with FISH.

Angelman Syndrome↗
PubMed1997

Proximal interstitial 6q deletion: a recognizable syndrome.

We report on an 8-year-old boy with a proximal interstitial deletion of the long arm of chromosome 6 with breakpoints q13 to q14.2. He has a characteristic facial appearance that is seen in several of the previously described cases. Details of his clinical course are reviewed and compared with the nine previous reported cases of the proximal deletion 6q syndrome.

Abnormalities, Multiple↗
PubMed1991

Ecological applications using a novel expert system shell.

Much of the information used by ecologists in modelling and decision making is imprecise. The imprecision arises both from data that are inexact or incomplete and from the use of ecological principles that are sometimes less than fully reliable and may be conflicting. Nevertheless, expert ecologists are able to construct usable models and make decisions that are used to manage and control ecological resources. This paper describes a unique expert system shell, developed in conjunction with user ecologists, which incorporates features enabling ecologists to represent knowledge and uncertainty in their expert systems in a way that is natural and appropriate. The reasoning mechanism was similarly developed in conjunction with user ecologists. It produces solutions to a class of expert level problems along with explanatory mechanisms and an appropriate analysis of the reasoning process. Three expert systems have been constructed by ecologists using this expert system shell. This enabled the shell designers to evaluate features for inclusion in the shell. The successful use of the shell by the ecologists has shown that significant economies arise when expert system shell design is tailored to use by a specific class of experts, in this case ecologists.

Ecology↗
PubMed1990

Variant Philadelphia translocations in chronic myeloid leukemia: correlation with cancer breakpoints, fragile sites and oncogenes.

Four cases of variant Philadelphia (Ph1) translocations were found in 72 patients (5.5%) with Ph1-positive chronic myeloid leukemia (CML). One previously unreported case was a simple variant translocation, namely, 46,XY,t(11;17)(q13;p13),t(17;22)(q25;q22); 46,XY,t(1;21)(q32;q11),t(11;17)(q13;p13), t(17;22)(q25;q11). Complex variant translocations were observed in three cases, namely, 46,XY,t(5;9;22)(q31;q34;q11),46,XX,t(8;9;22) (q22;q34;q11) and 46,XX,t(9;15;22) (q34;q15;q11). The chromosomal breakpoints in the cases of variant Ph1 translocations were the following: 1q32, 5q31, 8q22, 11q13, 15q15, 17p13, 17q25 and 21q11. Eight of the eight (100%) breakpoints were located in Giemsa-negative bands. Furthermore, seven of the eight (87%) variant Ph1 breakpoints correspond to the breakpoints present in consistent cancer arrangements. Three of the eight (38%) correspond to fragile sites and four of the eight (50%) correspond to oncogenes.

Genetic Variation↗
PubMed1988

Chromosome analysis in chorionic villi samples from the first trimester elective terminations.

Chorionic villi sampling (CVS) has become a first trimester alternative to amniocentesis for prenatal diagnosis. The cytogenetic findings in 150 experimental samples are presented. The ages of the mothers ranged from 12 to 35 years, but the majority of them were 18 and 19 years of age. Various parameters of culturing and processing the samples in order to improve the method, were investigated. Short term incubation for 48 h was the method routinely employed in processing the biopsies for cytogenetic analysis. In the first series of 100 cases one mosaic case (46,XX/45,X), one Robertsonian translocation (13;14), one marker chromosome and one fragment were found. The foetal tissues were not analysed for chromosomes. In the second series of 50 samples, one case of mosaicism was found in the chorionic villi (46,XX/47,XX, 18q-), but this abnormality was absent in the foetal tissue. One variant inv(9) was observed in the foetal tissue as well as in the chorionic villi. In all other cases the karyotypes from the chorionic villi samples matched those of the corresponding foetal samples. There was no maternal contamination in this series of 50 samples. The discrepancies in the cytogenetic results from other investigators are discussed.

Chorionic Villi↗
PubMed1987

Wrist arthroplasty: a retrospective study.

A retrospective study was conducted to evaluate the long-term effectiveness of wrist arthroplasties in patients with various arthritic conditions. A total of 39 wrist arthroplasties were performed in 29 patients (average age, 52.5 years) by the orthopedic staff at Tulane University School of Medicine. Rheumatoid arthritis was the major presenting diagnosis in 84.6% of these operative cases and pain was the most common indication for surgery (79.5%). Postoperative relief of pain was reported in all of the cases reviewed, with an average follow up period of 51.2 months (range, 12 to 118 months). A group of 15 patients who were examined clinically had an average grip strength of 19.2 lb (range, 6 lb to 45 lb). Pinch measurements averaged 1.9 lb and arc of motion averaged 59.5 degrees (range, 20 degrees to 100 degrees) for these patients. Postoperative complications included dislocation (3 cases), fracture of the prosthesis (2 cases), and infection (2 cases). No complications were observed in 32 (82.1%) of the 39 cases reviewed. This retrospective study revealed that at an average follow up period of 51.2 months, pain relief was excellent and patient acceptance was good, with 94.9% of the wrists having been improved by the procedure. The majority (82.1%) of the cases were free of complication. It is concluded from this study that wrist arthroplasty is a viable alternative to wrist arthrodesis.

Adult↗
PubMed1984

Computer-assisted instruction and diagnosis of radiographic findings.

Recent advances in computer technology, including high bit-density storage, digital imaging, and the ability to interface microprocessors with videodisk, create enormous opportunities in the field of medical education. This program, utilizing a personal computer, videodisk, BASIC language, a linked textfile system, and a triangulation approach to the interpretation of radiographs developed by Dr. W. L. Thompson, can enable the user to engage in a user-friendly, dynamic teaching program in radiology, applicable to various levels of expertise. Advantages include a relatively more compact and inexpensive system with rapid access and ease of revision which requires little instruction to the user.

Computer-Assisted Instruction↗