Amos, Boston U, USA Kitzis, CHU-Paris, France

Barker, U Alabama Birm, USA Klinger, Integ Genet, USA

Barton, Cambridge, England Knight, London, England

Barranger, Los Angeles, USA Lavinha, Lisboa Codex, Portugal

Beaudet, Baylor, USA Lissens, Vrije U Brussels

Boué, Paris, France Loukopoulos, Athens, Greece

Bowcock, Stanford, USA Lucotte, College de France

Cao, U Cagliari, Italy Malcolm, ICH-London, England

Carbonara, Torino, Italy Malik, Basler-Basel, Switzerland

Cassiman, U Leuven, Belgium Mao, Collab Res, USA

Claustres, Montpellier, France McIntosh, WGH-Edinburgh, Scotland

Collins, U Michigan, USA Morel, Lyon, France

Cutting, Johns Hopkins, USA Morgan, McGill, Canada

Dallapiccola, Roma, USA Naylor, UT San Antonio, USA

Dean, NCI Frederick, USA Olek, U Bonn, West Germany

De Arce, Dublin, Ireland Orr, U Minnesota, USA

Edwards, Oxford, England Pignatti, U Verona, Italy

Elles, St Mary's-Manchester, England Ramsay, SAMIR, South Africa

Erlich, Cetus, USA Richards, GeneScreen, USA

Estivill, Barcellona, Spain Romeo, Gaslini-Genoa, Italy

Ferec, Brest, France Rowley, Rochester, USA

Ferrari, Milano, Italy Rozen, Montreal Children, Canada

Godet, Villeurbanna, France Scheffer,UGroningen,TheNetherlands

Goossens, Creteil, France Schmidtke, IHG, Berlin

Graham, Belfast, N Ireland Schwartz, U Copenhagen, Denmark

Gruenert, UCSF, USA Sebastio, Naple, Italy

Halley, Rotterdam, The Netherlands Seltzer, U Colorado, USA

Harris, Guy's-London, England Spona, Viena, Austria

Highsmith, NC Mem Hosp, USA Super, Royal Manchester, England

Horst, Münster, West Germany Thibodeau, Rochester, USA

Jaume-Roig, Son Dureta, Spain Tümmler, Hannova, West Germany

Kalaydjieva, Sofia, Bulgaria Verellen-Dumoulin,Bruxelles,Belgium

Kant, U Penn, USA Williamson,St Mary'sLondon,England



NEWSLETTER #10, March 26, 1990


Dear members,

1. Xavier Estivill (Barcellona) has discovered a mutation (R334W) in exon 7 of the CF gene. He is also reporting flanking sequences of this exon. His letter is attached.

2. Burkard Tümmler (Hannova) reports that R553X mutation constitutes 10-20% of his collection of German non-[[Delta]]F508 CF chromosomes. He encourages consortium members to screen other populations.

3. Kerem, Zielensky and Tsui (Toronto) have identified 2 additional mutations, one in exon 10 (Q493X) and the other in exon 11 (S549I).

a. Q493X (nucleotide position 1609 C->T)- Gln493 (CAG) is changed into a stop codon (TAG) in Toronto family #9. The mutation occurs on a CF chromosome with haplotype IIIb; it is not found in 28 normal chromosomes (15 of which belong to IIIb) nor in 33 other CF chromosomes (5 of which IIIb). The mutation can be detected by allele-specific PCR, with 10i-5 as the common PCR primer, 5'-GGCATAATCCAGGAAAACTG-3' for the normal sequence and 5'-GGCATAATCCAGGAAAACTA-3' for the mutant allele. The PCR condition is 6 min at 94[[ring]] followed by cycles of 30 sec at 94[[ring]], 30 sec at 57[[ring]] and 90 sec at 72[[ring]], with 100 ng of each primer and ~400 ng genomic DNA. The primers 9i-3 and 9i-5 may be used for internal PCR control as they share the same reaction condition.

b. S549I (nucleotide position 1778 G->T)- The AGT->ATT change represents the third mutation involving this amino acid codon; the previous ones are AGT->AAT (S549N) and AGT->AGG (S549R). This position looks like a hot spot for mutation! This mutation also destroys a DdeI site, similar to G549N, and therefore one cannot distinguish the two by DdeI digestion. Fortunately (?), we have only one example who is of Arabic origin and is sequenced; no other DdeI-resistant chromosome is found in 5 other Arabic CF, 21 Jewish CF, 41 Canadian CF, and 13 Canadian normal chromosomes. Allele-specific PCR or ASO hybridization will be required to distinguish the two S549 mutations but, since both are mutant alleles, one may not care who is who. The same may not be true for other mutations, however, raising a serious drawback in using restriction enzyme digestion in genetic diagnosis.

4. Kerem et al. have found a G to A change for the last nucleotide of exon 10 (nucleotide position 1716) and 2 other groups (Ferec and Goossens) have also detected this change. We think that this nucleotide substitution is a sequence polymorphism because (a) it does not alter the amino acid, (b) it is unlikely to cause a splicing defect and (c) it occurs on a normal chromosome. In both Canadian families, this rare allele is found associated with haplotype IIIb.

5. Many members have already responded to the request of an update of the [[Delta]]F508 mutation data. For those who have not, please send in your data as soon as possible, indicating (1) total CF chromosomes screened; (2) number of those with [[Delta]]F508; (3) the percentage; and (4) geographic location or ethnic distribution, regardless what you have sent previously, and the names of individuals that need to be included in the publication. As explained in the previous newsletter, the report will appear under the name of the Consortium with all authors listed as a footnote; the maximal number of authors per group is 3, with simplified affiliations containing only names of institutes, city, and country. The last day of acceptance is March 30. A draft of the report will be distributed on April 2 and the final sent off to Am. J. Hum. Genet. on April 4.

6. An updated list of CF mutations is attached (a good copy will be followed by regular mail and the [[Delta]]F508 summary table for the joint report will be published in the next issue of newsletter). There were 2 errors in the previous reports:

a. For the R560T mutation, the arginine codon 560 should read AGA and the mutant should be ACT (Newsletter #5, 2d). The mutation may also affect splicing. Thanks to Luba Kalaydjieva and Garry Cutting for pointing these out.

b. The mutation at amino acid at position 347 is R to P (nucleotide G1173 to C, not D to P (see Dean's letter, Newsletter #7).

7. A list of consortium members is attached (a good copy will be followed by regular mail). I would like to take this opportunity to emphasize once again that this consortium is meant to be a working group whose objectives are to facilitate identification of additional CF mutations and to collect population data. Please do not encourage others to join in order to receive newsletters for any other purpose.

8. Some members have raised the question about reporting at meetings and in literature on interesting cases using mutation information from the Consortium. It is a complex issue as many of the original reports on the identification of non-[[Delta]]F508 mutations have yet to be accepted for publication. We will need to have a general consensus on this subject but, in the mean time, I think submission of any secondary papers should not preceed (the acceptance of) the original report.

Best regards,

Lap-Chee Tsui