394 MUTATION NOTES

single-strand conformational polymorphism (SSCP) analysis, 22 exons and 196 bp of the 5' region of the PDEB gene were screened. Primers were derived from Riess et al. (1992). The samples corresponding to the two affected RP patients had an altered migration band in exon 13 compared with controls while the SSCP pattern in both parents suggested that they are heterozyguous carriers of the mutation. Sequence analysis was performed on the PCR product of exon 13 and a G-to-A transition in codon 552 was detected. This change results in the substitution of a hydrophilic arginine aminoacid by a neutral glutamine residue.

Rod photoreceptor cell cGMP-specific PDE is a key enzyme in phototransduction. Inactivation of PDE by mutations in PDEB would lead to accumulation of rod cGMP, and it has been suggested that this is deleterious for the photoreceptor cells (Lolley et al., 1977). The catalytic site of the cGMP hydrolysis has been assigned to the peptide region between residues 555-790 in the human protein. Therefore, the G-to-A change close to this catalytic core would involve a modification in the structural conformation of the protein that would disturb the physiological hydrolysis of cGMP.

ACKNOWLEDGMENTS

Espafiol). This work was supported by FIS (95/1953) and FAARPE (Federacibn de Asociaciones de Afectados por Retinosis Pigmentaria del Estado

REFERENCES Bay& M, Giordano M, Balcells S, Grinberg D, Vilageliu LI, Martinez I, Ayuso C, Benitez J, Ramos MA, Chivelet P, Solans T, Valverde D, Anselem S,

GoL..ssens M, Baiget M, Gonzdez-Duarte R, Besmond C (1995) Homozygous tandem duplication within the gene encoding the p subunit of rod phos- phodiesterase as a cause for autosomal recessive retinitis pigmentosa. Hum Mutat 5228-234.

Lolley RN, Farher DB, Rayborn ME, Hollyfield JG (1977) Cyclic GMP accumulation causes degeneration of photoreceptor cells: Simulation of an inherited disease. Science 196:664-666.

Riess 0, Noerremoelle A, Weber B, Musarella MA, Hayden MR (1992) The search for mutations in the gene for the beta subunit of the cGMP phosphodiesterase (PDEB) in patients with autosomal recessive retinitis pigmentosa. Am J Hum Genet 51:755-762.

Valverde D, Solans T, Grinberg D, Balcells S, Vilageliu LI, Bay& M, Chivelet P, Besmond C, Gwssens M, Gonz4lez-Duarte R, Baiget M (1996) A novel mutation in exon 17 of the p subunit of rod phosphodiesterase in two RP sisters of a consanguineous family. Hum Genet 97:35-38.

A Common Base Change in the Promoter Region of the Human Endothelial NO-Synthase (NOS3) Gene; Johannes Meier, Maja Affeldt, Christian Opitz, Franz X. Kleber, and Astrid Speer', HumboldtJJniuersiry, Churite, I. Medidnische KliniklKardiobgie, D-I01 17 Berlin, Germany; Fax: 49-30-2802-6531 Communicated b j Jiirgen Horst Received November 6, 1995; accepted December 20, 1995. 0 1996 Wiley-Liss, Inc. 'To whom reprint requestslcorrespondence should be addressed.

In several cardiovascular diseases, such as atherosclerosis, hypertension, or heart failure the endothelial NO signaling system appears to be abnormal (Moncada et al., 1991). In a search for genetic variants contributing to such diseases, we examined the shear stress response elements in the promoter region and the calcium binding domain in exons 11 and 12 of the NOS3 gene (Nadaud et al., 1994). A base exchange A-946 G was found in the promoter region by PCR (F-TGTCTGTCTGCTGCTCCAG; R-CTCTCCAGGCACXTCAGGC), SSCP (lo%, 1IoC, 35 W) and automatic sequencing (Applied Biosystems, model 373A). Ninety-nine caucasion control subjects showed an allele distribution of 41.4% A, 42.4% NG, and 16.2% G. Association studies are necessary to determine the possible functional implications of this polymorphism with respect to endothelial function.

REFERENCES Moncada, S, Palmer RMJ, Higgs EA (1991) Nitric oxide: physiology, pathophysiology, and pharmacology. Phamacol Rev 43:109-142. Nadaud S, Bonnardeaux A, Lathrop M, Soubrier F (1994) Gene structure, polymorphism and mapping of the human endothelial nitric oxide synthase gene.

Biochem Biophys Res Commun 1981027-1033.

Frameshift Mutation at Codon 642 of the hMLHl Gene in Human Endometrial Cancer; Shinichi Fukushige, Shigeru Wakatsuki, Satoru Nagase, and Akira Horii', Department of Molecular Pathology, Tohku University School of Medicine, Sendai 980-77, Japan; Fax 81-22-717-8047 Communicated Kemhi Hayashi Received September 22, 1995; accepted December 22, 1995. 0 1996 Wiley-Liss, Inc. 'To whom reprint requestdwnespondence should he addressed.

Eighteen endometria1 cancers with RER( + ) phenotype were examined to search for any of the mutations in hMSH2 and hMLHl using single-strand conformation polymorphism analysis coupled with polymerase chain reaction (PCR-SSCP) (Orita et al., 1989). Primers for PCR amplification were selected according to Liu et al. (1994) and Han et al. (1995) for hMSH2 and hMLHI, respectively. After examining the entire coding regions of these two genes, DNA in a case of endometrial cancer (tumor 83) showed an aberrant pattern in exon 1 7 of the hMLHI gene; two extra bands were clearly observed. Since this abnormal pattern was not found in DNA of normal tissue in this patient, it was evident that a somatic mutation occurred in this tumor. DNAs were extracted from these extra bands and their nucleotide sequences along with a DNA sample of normal tissue were determined. Results clearly demonstrated a somatic 2,base pair deletion of either TC or CT