[Dissection and cytogenetic localization of the phenotypes of the 5p deletion syndrome]

OBJECTIVE

To classify the phenotypes of the short arm of chromosome 5 (5p) deletion syndrome and to localize their corresponding regions in the human genome.

METHODS

A hundred and six patients, together with most of their parents and sibs, were analysed both cytogenetically and clinically. The dissection of the syndrome and cytogenetic localization of each phenotype was made by relating the clinical data to the breakpoints involved in the deletions.

RESULTS

The 5p deletion syndrome was classified into 8 types based on the combination of the clinical data and high-resolution banding analysis.

CONCLUSIONS

The dissection of the "5p deletion syndrome", a term with refined concept suggested by us, and the cytogenetic localization of each distinct phenotype will provide the clear cut criteria for clinical and cytogenetic diagnosis of the 5p-patients, as well as the candidate regions for positional cloning of the gene(s) repossible for the phenotypes.

Molecular definition of deletions of different segments of distal 5p that result in distinct phenotypic features

Cri du chat syndrome (CDC) is a segmental aneusomy associated with deletions of chromosome 5p15. In an effort to define regions that produce the phenotypes associated with CDC, we have analyzed deletions from 17 patients. The majority of these patients had atypical CDC features or were asymptomatic. Using these patients, we have mapped several phenotypes associated with deletions of 5p, including speech delay, catlike cry, newborn facial dysmorphism, and adult facial dysmorphism. This phenotypic map should provide a framework with which to begin identification of genes associated with various phenotypic features associated with deletions of distal 5p. We have also analyzed the parental origin of the de novo deletions, to determine if genomic imprinting could be occurring in this region. In addition, we have isolated cosmids that could be useful for both prenatal and postnatal assessments of del5(p) individuals.