Biomedical subjects
Publications and source records attributed to M Preus.
An oculocerebral hypopigmentation syndrome consisting of growth retardation, dolichocephaly, cataracts, high arched palate, small, widely spaced teeth, generalized hypopigmentation, psychomotor retardation, progressive neurological manifestations and hypochromic anemia is described in sibs. The finding of parental consanguinity supports autosomal recessive inheritance. The syndrome resembles the Cross syndrome (1,2).
We have made use of eight phenotypic findings of Down syndrome to develop an effective diagnostic index. We estimate that about 95% of patients who are suspected of having the syndrome can be categorized as having or not having it with 99.9% confidence. One can thereby make a fast clinical diagnosis on the majority of suspects before karyotyping is complete, allowing one to inform parents soon after birth and, in some instances, to make medical decisions about life-threatening defects. Furthermore, one can avoid the expense of chromosome studies on most patients who do not have the syndrome, unless there are other indications for chromosome studies. The eight features used in the index include three dermatoglyphic traits (hallucal and forefinger pattern, and palmar triradius), two measurements of physical traits (ear length and internipple distance), and three other clinical findings (Brushfield spots, wide-spaced first toe, and excess back neck skin).
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The hand pattern profiles of 18 previously published and 10 new cases of de Lange syndrome were compared to those of cases referred as suspects, but judged clinically and by numerical taxonomic methods not to have de Lange syndrome (non-de Lange). Based on a Poznanski metacarpophalangeal profile of the 2 groups of patients, a simple scoring system using 11 measurements was devised using the 16 most marked differences within and between metacarpals and phalanges. Of the metacarpals, the first is shorter than the second, third, fourth, or fifth; and the second and fifth are shorter than the third or fourth. Of the middle phalanges, the third and fourth are shorter than the respective metacarpal and than the second and fifth middle phalanx. Of the distal phalanges, the fifth is shorter than the second. The mean Z score for these 11 measurements is further below normal in the de Lange group than in the non-de Lange group. All 11 non-de Lange patients had a score less than 17, and all 28 de Lange patients had a score of 18 or more.
Syndrome classification may be described as the arrangement of individuals into groups on the basis of their phenotypic resemblance. This paper describes how phenotypic resemblance may be quantified and demonstrates a numerical method called distorted shell clustering, which isolates groups of phenotypically similar individuals representing syndromes. This new method takes into consideration apparent biological properties of syndromes. It allows for overlapping phenotypes between syndromes, and differing character association and variability within syndromes. This method is compared to four other clustering methods by using suspects for a syndrome of known etiology (Down syndrome). The numerical results based on the phenotype then can be compared with the actual diagnosis. Only the distorted shell method classifies patients, without error, into two major clusters: the Down and the non-Down, while maintaining a high level of efficiency.
We describe two infants with the cerebro-oculofacio-skeletal syndrome in whom oligohydramnios is an additional finding. The oligohydramnios could be accounted for in one by renal agenesis but cannot in the other, who had a functioning and histologically normal kidney. The diagnosis of Potter syndrome was suspected in both patients. It is important in counseling to recognize the distinctive phenotype of this autosomal-recessive syndrome.
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A simple and effective index for the diagnosis of Down syndrome is presented. It makes use of 12 characters with from two to nine states. The simple format allows persons with limited knowledge of the characters to use it. Simplicity was attained by combining character states when this did not result in a loss of discrimination and by avoiding characters that were redundant, subject or difficult to evaluate. A combination of characters that occur frequently in Down syndrome (wide applicability and characters that have a high relative frequency (high probability) was used. Additional data from comparable samples were used to calculate more representative scores for some characters. Over 82% of suspected cases may be diagnosed as having or not having Down syndrome with 99.9% confidence. Conditional probabilities for the various scores are provided. Individuals whose scores are in the Down or non-Down zones have a 98.7% probability or greater of having or not having the syndrome, respectively. The index is more effective than others as measured both by the percentage of individuals with and without Down syndrome whose scores fall into distinct zones (overlap method) and by the percentage with Down syndrome who have positive scores and controls who have negative scores (single point classification).
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An index has been devised using dermatoglyphics and selected physical traits to screen for patients suspected of having Turner syndrome. About 60% of females with and without Turner syndrome can be diagnosed as having or not having the syndrome with a 98% or greater probability. The patient's score on the index, expressed in probability, can be used to decide whether chromosome studies should be done. Using the approach demonstrated in this pilot study, the discriminative power can be increased by adding more features and by enlarging the sample to permit division of features into more discriminating classes.
A method has been developed to test for heterogeneity in syndromes of unknown etiology and to distinguish between patients with and without the syndrome. The validity of the method was tested on a group of patients suspected of having a syndrome that can be diagnosed by other means (Down syndrome), and was found to be effective. The method was then applied to a group of patients suspected of having a syndrome of unknown etiology (de Lange). It was shown that the group appears to be heterogeneous. A preliminary diagnosis of having or not having the syndrome was made in about 80% of the patients.
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