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P Dignan

Publications and source records attributed to P Dignan.

6 recordsLinked to original sources
PubMed1994

Down syndrome phenotypes: the consequences of chromosomal imbalance.

Down syndrome (DS) is a major cause of mental retardation and congenital heart disease. Besides a characteristic set of facial and physical features, DS is associated with congenital anomalies of the gastrointestinal tract, an increased risk of leukemia, immune system defects, and an Alzheimer-like dementia. Moreover, DS is a model for the study of human aneuploidy. Although usually caused by the presence of an extra chromosome 21, subsets of the phenotypic features of DS may be caused by the duplication of small regions of the chromosome. The physical map of chromosome 21 allows the molecular definition of the regions duplicated in these rare cases of partial trisomy. As a first step in identifying the genes responsible for individual DS features and their pathophysiology, a panel of cell lines derived from 16 such individuals has been established and the molecular break points have been determined using fluorescence in situ hybridization and Southern blot dosage analysis of 32 markers unique to human chromosome 21. Combining this information with detailed clinical evaluations of these patients, we have now constructed a "phenotypic map" that includes 25 features and assigns regions of 2-20 megabases as likely to contain the genes responsible. This study provides evidence for a significant contribution of genes outside the D21S55 region to the DS phenotypes, including the facies, microcephaly, short stature, hypotonia, abnormal dermatoglyphics, and mental retardation. This strongly suggests DS is a contiguous gene syndrome and augurs against a single DS chromosomal region responsible for most of the DS phenotypic features.

Blotting, Southern↗
PubMed1987

Recurrent developmental anomalies: 1. Syndrome of hydranencephaly with renal aplastic dysplasia; 2. Polyvalvular developmental heart defect.

We present 2 examples of previously apparently undescribed congenital anomalies that recurred in a subsequent pregnancy. In one case this was a multiple-congenital-anomalies syndrome of hydranencephaly with multinucleated neurons, hypoplastic kidneys, and syndactyly of the second and third toes. The second case involved atrioventricular valve thickening resulting in tricuspid insufficiency and mitral stenosis. These cases suggest that if after a complete autopsy the findings are unprecedented, then the recurrent risk in a subsequent pregnancy may be high. This hypothesis has not been tested prospectively.

Abnormalities, Multiple↗
PubMed1983

Prune perineum syndrome: report of a second case.

A child is reported with a constellation of anomalies which include acetabular dysplasia with bilateral dislocated hips, persistent cloaca, hypoplastic kidney, two umbilical vessels, anal atresia and no obvious external genitalia. These anomalies are strikingly similar to a case reported by Peeden et al ('79) which was referred to as prune perineum. A discussion on possible underlying cause(s) of caudal dysplasia is included.

Abnormalities, Multiple↗