Malformation syndromes--a diagnostic approach

The natural history of Cri du Chat Syndrome. A report from the Italian Register

The aim of this report is to provide an update on the natural history of the Cri du Chat Syndrome by means of the Italian Register (I.R.). Two hundred twenty patients were diagnosed by standard cytogenetic methods and 112 of these were also characterised by molecular-cytogenetic investigation (FISH). FISH analysis showed interstitial deletions, short terminal deletions and other rare rearrangements not previously correctly diagnosed by standard cytogenetics. The diagnosis was made in the first month of life in 42% and within first year in 82% of cases. The remaining 18% were diagnosed at an age ranging from 13 months to 47 years. At the last follow-up, patient age ranged from 8 months to 61 years. Mortality, already low, has decreased over time as it is lower between 1984-2002 compared to 1965-1983. Mortality was higher in patients with unbalanced translocations resulting in 5p deletions. Our data confirm that the cat-like cry and peculiar timbre of voice are the most typical signs of the syndrome, not only at birth but also later and these are the only signs which might suggest the diagnosis in patients with small deletions and mild clinical picture. A cytogenetic and clinical variability must be underlined. Cardiac, cerebral, renal and gastrointestinal malformations were more frequent in the patients with unbalanced translocations resulting in 5p deletions. Sucking and feeding difficulties and respiratory infections are frequent in the first months or years of life. Intubation difficulties linked to larynx anomalies must be considered. Psychomotor development is delayed in all patients but there is a variability related to deletion size and type as well as other genetic and environmental factors. However, the results showed an improvement in the acquisition of the development skills and progress in social introduction which should encourage caregivers and parents to work together in carrying out the rehabilitative and educational interventions.

Clinical and molecular characterisation of 80 patients with 5p deletion: genotype-phenotype correlation

The majority of deletions of the short arm of chromosome 5 are associated with cri du chat syndrome (CdCS) and patients show phenotypic and cytogenetic variability. To perform a genotype-phenotype correlation, 80 patients from the Italian CdCS Register were analysed. Molecular cytogenetic analysis showed that 62 patients (77.50%) had a 5p terminal deletion characterised by breakpoint intervals ranging from p13 (D5S763) to p15.2 (D5S18). Seven patients (8.75%) had a 5p interstitial deletion, four (5%) a de novo translocation, and three (3.75%) a familial translocation. Of the remaining four patients, three (3.75%) had de novo 5p anomalies involving two rearranged cell lines and one (1.25%) had a 5p deletion originating from a paternal inversion. The origin of the deleted chromosome 5 was paternal in 55 out of 61 patients (90.2%). Genotype-phenotype correlation in 62 patients with terminal deletions highlighted a progressive severity of clinical manifestation and psychomotor retardation related to the size of the deletion. The analysis of seven patients with interstitial deletions and one with a small terminal deletion confirmed the existence of two critical regions, one for dysmorphism and mental retardation in p15.2 and the other for the cat cry in p15.3. Results from one patient permitted the cat cry region to be distally narrowed from D5S13 to D5S731. Furthermore, this study lends support to the hypothesis of a separate region in p15.3 for the speech delay.

Standard method of diagnosis versus use of a computer database in the evaluation of skeletal dysplasias

OBJECTIVE

The objective of this study was to compare reference textbooks and the computer database, OSSUM, for accuracy and ease of use in the diagnosis of skeletal dysplasias. Materials and methods. Twenty cases of clinically and and radiologically established skeletal dysplasias were evaluated as unknowns by four pediatric radiologists. Readers 1 and 2 evaluated group A (10 cases) using reference texts and group B (10 cases) using OSSUM. Readers 3 and 4 evaluated group B using reference texts. The radiologists independently listed their roentgenographic findings, the top three diagnoses, confidence level, difficulty level, and time spent on each case.

RESULTS

The correct diagnosis was made in 68% of both the reference text cases and the OSSUM cases. Difficulty level was significantly higher (3.5 vs 2.9, P = 0.0013) and confidence significantly lower (3.3 vs. 2.3, P = 0.0001) when using OSSUM. Average time spent on cases was 25 min with references and 30 min with OSSUM (P > 0.05). However, there was a decrease in both the time (38 min vs 23 min, P = 0.05) and the difficulty (3.9 vs 3.1, P = 0.001) between the first five and the last five cases. The composite of four readers correctly identified 90% of the skeletal dysplasias when the results of both methods were combined.

CONCLUSIONS

In the ability to reach a correct diagnosis, no difference was detected between the OSSUM and reference texts methods. The increased time necessary, greater difficulty and decreased confidence levels with OSSUM are expected to improve with increasing program familiarity. Use of both textbooks and the database was complementary.

Programs, databases, and expert systems for human geneticists--a survey

We present an overview of the variety of databases and programs that offer substantial aid to medical and molecular geneticists. Databases and expert systems for genetic diseases and birth defects, programs for segregation and linkage analysis, certain DNA and protein sequence databases, and information resources in general for molecular biology are addressed. These systems cannot be used effectively without the newly developed techniques of information exchange based on international computer networks. A short introduction is given to the Internet and to European institutions and organizations that offer help with the acquisition and use of bioinformatic resources.

A case-based assistant for diagnosis and analysis of dysmorphic syndromes

This report describes the development of a case-based reasoning (CBR) system designed to provide assistance to specialists within the dysmorphology field. An interactive CBR model is described which aids medical experts in arriving at potential diagnoses, and has an explicit learning goal in order to provide further analytical assessment of syndrome categories. The complexity of this real world domain has highlighted a number of important empirical issues with respect to CBR techniques, which are discussed along with the system design.

The diagnosis of syndromes by use of a dysmorphology database

A dysmorphology data base can be useful for the clinician in the task of diagnosing multiple malformation syndromes in children. In this article the database POSSUM is described. Four patients with multiple anomalies referred for diagnostic syndrome evaluation are presented. They serve as examples on how POSSUM efficiently can be applied to obtain a short list of appropriate alternative syndromes, subsequently followed by a discussion on the differential diagnosis in each case. A specific, rare syndrome was diagnosed with the aid of POSSUM in all four cases. POSSUM appears to be useful for the diagnosis of dysmorphic syndromes.