Schlagwort-Archive: Genome Editing

Phenotype of the CRISPR CAS babies

CCR5 annotation, including the known delta32 Mutation and the three mutations introduced by He Jiankui. PAM=Protospacer adjacent motif, DSB=putative double strand break.

From the CCR5 sequence we get the following amino acid sequences

>sp|WT.P51681|CCR5_HUMANC-Cchemokinereceptortype5OS=HomosapiensOX=9606GN=CCR5PE=1SV=1
MDYQVSSPIYDINYYTSEPCQKINVKQIAARLLPPLYSLVFIFGFVGNMLVILILINCKR
LKSMTDIYLLNLAISDLFFLLTVPFWAHYAAAQWDFGNTMCQLLTGLYFIGFFSGIFFII
LLTIDRYLAVVHAVFALKARTVTFGVVTSVITWVVAVFASLPGIIFTRSQKEGLHYTCSS
HFPYSQYQFWKNFQTLKIVILGLVLPLLVMVICYSGILKTLLRCRNEKKRHRAVRLIFTI
MIVYFLFWAPYNIVLLLNTFQEFFGLNNCSSSNRLDQAMQVTETLGMTHCCINPIIYAFV
GEKFRNYLLVFFQKHIAKRFCKCCSIFQQEAPERASSVYTRSTGEQEISVGL

>sp|-32.P51681|CCR5_HUMANC-Cchemokinereceptortype5OS=HomosapiensOX=9606GN=CCR5PE=1SV=1
MDYQVSSPIYDINYYTSEPCQKINVKQIAARLLPPLYSLVFIFGFVGNMLVILILINCKR
LKSMTDIYLLNLAISDLFFLLTVPFWAHYAAAQWDFGNTMCQLLTGLYFIGFFSGIFFII
LLTIDRYLAVVHAVFALKARTVTFGVVTSVITWVVAVFASLPGIIFTRSQKEGLHYTCSS
HFPY
IKDSHLGAGPAAACHGHLLLGNPKNSASVSK

>sp|-15.P51681|CCR5_HUMANC-Cchemokinereceptortype5OS=HomosapiensOX=9606GN=CCR5PE=1SV=1
MDYQVSSPIYDINYYTSEPCQKINVKQIAARLLPPLYSLVFIFGFVGNMLVILILINCKR
LKSMTDIYLLNLAISDLFFLLTVPFWAHYAAAQWDFGNTMCQLLTGLYFIGFFSGIFFII
LLTIDRYLAVVHAVFALKARTVTFGVVTSVITWVVAVFASLPGIIFTRSQKEGLHYTCS
SQYQFWKNFQTLKIVILGLVLPLLVMVICYSGILKTLLRCRNEKKRHRAVRLIFTI
MIVYFLFWAPYNIVLLLNTFQEFFGLNNCSSSNRLDQAMQVTETLGMTHCCINPIIYAFV
GEKFRNYLLVFFQKHIAKRFCKCCSIFQQEAPERASSVYTRSTGEQEISVGL

>sp|-4.P51681|CCR5_HUMANC-Cchemokinereceptortype5OS=HomosapiensOX=9606GN=CCR5PE=1SV=1
MDYQVSSPIYDINYYTSEPCQKINVKQIAARLLPPLYSLVFIFGFVGNMLVILILINCKR
LKSMTDIYLLNLAISDLFFLLTVPFWAHYAAAQWDFGNTMCQLLTGLYFIGFFSGIFFII
LLTIDRYLAVVHAVFALKARTVTFGVVTSVITWVVAVFASLPGIIFTRSQKEGLHYTCSS
HFP
YSINSGRISRH

>sp|+1.P51681|CCR5_HUMANC-Cchemokinereceptortype5OS=HomosapiensOX=9606GN=CCR5PE=1SV=1
MDYQVSSPIYDINYYTSEPCQKINVKQIAARLLPPLYSLVFIFGFVGNMLVILILINCKR
LKSMTDIYLLNLAISDLFFLLTVPFWAHYAAAQWDFGNTMCQLLTGLYFIGFFSGIFFII
LLTIDRYLAVVHAVFALKARTVTFGVVTSVITWVVAVFASLPGIIFTRSQKEGLHYTCSS
HFPY
KSVSILEEFPDIKDSHLGAGPAAACHGHLLLGNPKNSASVSK

The -15/WT genotype will have both, a normal and a slightly shortened CCR5 giving no HIV protection at all. The -4/+1 genotype may suffer the fate of non-sense mediated decay. Here are the amino acid predictions for each genotype (I reverted to Topcocns as Protter had some problems in generating correct plots).

Wildtype: There are 7 transmembrane alpha helices I to VII, connected by three extracellular loops (ECL1–3) and three intracellular loops (ICL1–3). ECL2, forms a β-hairpin structure (Tan 2013).
Known delta 32
Nana -4 genotype has a much shorter predicted amino acid sequence with missing G protein coupling. Resembles delta 32.
Nana +1 genotype is somewhat longer but missing helices VI and VII. No analogue known.
Lulu -15: resembles wild type, however, will be sensitive to allosteric changes by small-molecule CCR5 inhibitors .

From the original AJHG paper, however, also delta 32 carriers may be HIV infected. As there exists also non-CCR5 dependent virus replication, also Nana is at risk of HIV infection when being virus exposed.

Geschützt: Der chinesische Menschenversuch

Dieser Inhalt ist passwortgeschützt. Um ihn anschauen zu können, bitte das Passwort eingeben:

More human embryos edited

technologyreview.com writes

Now Mitalipov is believed to have broken new ground both in the number of embryos experimented upon and by demonstrating that it is possible to safely and efficiently correct defective genes that cause inherited diseases.
Although none of the embryos were allowed to develop for more than a few days—and there was never any intention of implanting them into a womb—the experiments are a milestone on what may prove to be an inevitable journey toward the birth of the first genetically modified humans. […] Reached by Skype, Mitalipov declined to comment on the results, which he said are pending publication. But other scientists confirmed the editing of embryos using CRISPR. “So far as I know this will be the first study reported in the U.S.”

For a few moments of fame, scientists take every risk, even “mass destruction and proliferation”.
It reminds me to the first gene therapy trial by French Anderson who was later stripped of tenure, fired from his faculty position and barred from the campus of his university.

Safety conditions for genome editing

I would like to see two points added to current CRISPR/Cas9 guidelines.

First of all, the current gene therapies are not being entered into the clinical trial databases on a regular basis. Maybe as the number of treated patients go down to a single individual or as there is no control group. I would really like the recommendation of a priori entry into clinicaltrials.gov or clinicaltrialsregister.eu (or some newly designed gene therapy databases). Just to get towards a clear risk/ benefit ratio.

Second, there should be some way to recognize gene editing. Some barcode as we used it already long ago, an artificial sequence that indicates the new insert. epigenie.com summarized the current approaches by last summer: Gestalt/Jay Shendure, barcode/Stephen R. Quake, scartrace/Jan Philipp Junker, hgRNA/Prasant Mali, mScribe/Tim Lu. Something like the FLAG-tag. Or more recently

R. Kalhor et al., “Rapidly evolving homing CRISPRbarcodes,” Nature Methods, doi:10.1038/nmeth.4108, 2016.
S.D. Perli et al., “Continuous genetic recording with self-targeting CRISPR-Cas in human cells,” Science, doi: 10.1126/science.aag0511, 2016.

 

Gene Doping using CRISPR/Cas

After some first  experiments in human embryos, there is a new Chinese paper in the Journal of Molecular Biology showing that also gene doping is possible in mammals.  Myostatin deficiency otherwise leads to some really impressive super strength children while it is now possible to knockout this gene artificially.  Hopefully the WADA will test for myostatin gene activity in Rio 2016!
Addendum 4 Dec15: An International Summit Statement On Human Gene Editing says

It would be irresponsible to proceed with any clinical use of germline editing unless and until (i) the relevant safety and efficacy issues have been resolved, based on appropriate understanding and balancing of risks, potential benefits, and alternatives, and (ii) there is broad societal consensus about the appropriateness of the proposed application.

Both conditions are unlikely to be ever met.