The 18q deletion (18q-) syndrome (OMIM #601808), caused by deletion of the distal long arm of chromosome 18 is a terminal deficiency or macrodeletion syndrome characterized by mental retardation and congenital malformations. It can be interpreted as having its basis in haploinsufficiency of multiple genes. The phenotype is highly variable, but is characterized by mental retardation, short stature, hypotonia, hearing impairment, and foot deformities. The syndrome is often accompanied by selective IgA deficiency and associated autoimmune disease. The contribution of individual genes within the region to specific phenotypic features can be modeled, because the occurrence or severity of these symptoms correlate with the extent of the deletion. The power of such studies depends on the size, diversity, and level of characterization of the study population. For some time the NIGMS Repository has held and distributed twenty 18q- lymphoblastoid cell lines (LCLs) and seven (7) human-rodent somatic cell hybrids (SCHs) which include the 18q- deletion chromosome. Now with the acquisition of a unique collection of seventy seven (77)18q- (LCLs) and twenty seven (27) SCHs from Dr. Joan Overhauser this particular NIGMS resource is greatly enhanced.

The value of the newly acquired materials lies in the extensive characterization of their deletion breakpoints by molecular cytogenetics and molecular genetic methods, together with the detailed clinical documentation of the donor phenotypes that is available. Given the great diversity of phenotypes encompassed in this condition this collection is the definitive resource for genotype-phenotype studies of the 18q deletion syndrome, and also for gene discovery.

The materials are presented so that the chromosomal, molecular and clinical data of each incremental 18q- deletion are displayed together for review.

References

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