Exhibit 3.2(aa)

"CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS DOCUMENT
IDENTIFIED BY *** HAVE BEEN OMITTED AND HAVE BEEN SEPARATELY FILED WITH THE
COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE
OMITTED PORTIONS."

EXTENSION AGREEMENT dated July 27, 2005

BETWEEN

AUTOGEN RESEARCH PTY LIMITED(1) ABN 84 074 636 847 of Pigdons Road, Waurn Ponds
Victoria 3217, Australia ("AUTOGEN RESEARCH")

AND

SOUTHWEST FOUNDATION FOR BIOMEDICAL RESEARCH of 7620 NW Loop, 410 San Antonio,
Texas 78227-5301, USA ("SFBR")


RECITALS

A.       On 31 December 2002 Autogen Research and SFBR entered into an agreement
         entitled Research, License and Commercialization Agreement (the
         "Research Agreement") setting out the terms and conditions for the R&D
         Program to be carried out with the participation of the parties.

B.       In accordance with clause 20.3 of the Research Agreement the parties
         now agree to vary the Research Agreement on the terms and conditions
         set out in this Extension Agreement.


OPERATIVE PROVISIONS

1.       INTERPRETATION

1.1      RESEARCH AGREEMENT DEFINITIONS

         Unless defined in this Extension Agreement, words and phrases defined
         in the Research Agreement have the same meaning in this Extension
         Agreement. Where there is any inconsistency in a definition between
         this Extension Agreement and the Research Agreement, this Extension
         Agreement prevails.

1.2      INTERPRETATION

         The provisions of clause 1.2 of the Research Agreement apply to this
         Extension Agreement as if set out in this Extension Agreement in full.

2.       EXTENSION AGREEMENT

2.1      EXTENSION OF TERM
         With effect on and from 1 July 2005 the parties agree that the term of
         the Research Agreement is extended until 31 December 2005 ("EXTENDED
         TERM") (unless the Research Agreement is earlier

--------
(1) Autogen Research Pty Ltd is a wholly-owned subsidiary of ChemGenex
Pharmaceuticals Limited (ABN 79 000 248 304).


<PAGE>

         terminated in accordance with its terms). During the Extended Term the
         terms and conditions of the Research Agreement will continue to apply
         except to the extent to which they are inconsistent with anything set
         out in this Agreement, in which case the provisions of this Agreement
         will prevail to the extent of the inconsistency.




2.2      PAYMENT AND RESEARCH PROPOSAL DURING EXTENDED TERM
         During the Extended Term:

         (a)      the budget set out in Schedule 1 to this Extension Agreement
                  will be substituted for any payment program previously
                  applying under the Research Agreement; and

         (b)      the research plan (including any milestones set out therein)
                  set out in Schedule 2 to this Extension Agreement will be
                  substituted for any research proposal and workplans previously
                  applying under the Research Agreement.

3.       MISCELLANEOUS

3.1      CONTINUING EFFECT

         Except for the variations set out in this Extension Agreement, the
         terms and conditions of the Research Agreement are unaffected by this
         Extension Agreement and remain in full force and effect. In the event
         of any inconsistency between the terms of the Research Agreement and
         the terms of this Extension Agreement, the terms of this Extension
         Agreement will prevail to the extent of the inconsistency.
3.2      FURTHER ASSURANCES

         Each party must do all things and execute all further documents
         necessary to give full effect to this Extension Agreement and must
         refrain from doing anything that might hinder the performance of this
         Extension Agreement.
3.3      AMENDMENTS IN WRITING

         No amendment to this Extension Agreement has any force unless it is in
         writing and signed by both of the parties to this Extension Agreement.
3.4      GOVERNING LAW AND JURISDICTION

         This Extension Agreement is governed by the laws of Victoria and the
         Commonwealth of Australia. Each party irrevocably submits to the
         exclusive jurisdiction of the courts of Victoria.
3.5      COUNTERPARTS AND FACSIMILE EXECUTION

         This Extension Agreement may be executed in a number of counterparts,
         all of which taken together will be deemed to constitute one and the
         same agreement, provided that this Extension Agreement will be of no
         force and effect until the counterparts are exchanged. A facsimile copy
         of this Extension Agreement lawfully executed will be sufficient
         evidence of execution.

                                       2
<PAGE>


EXECUTED as an AGREEMENT



<TABLE>
<CAPTION>
SIGNED on behalf of                       )
AUTOGEN RESEARCH PTY LIMITED              )
ABN 84 074 636 847 by GREG COLLIER in the )
presence of:                              )
<S>          <C>        <C>        <C>         <C>      <C>          <C>
                                                                       -------------------------------------------------
                                                                   /~  Signature of Greg Collier
                                                                       Director

         ---------------------------------------------------
     /~
         Signature of witness
         ---------------------------------------------------
     /~
         Name of witness (print)



SIGNED on behalf of                     )
SOUTHWEST FOUNDATION FOR                )
BIOMEDICAL RESEARCH by                  )
                         in the presence)
of:                                     )
                                                                       -------------------------------------------------
                                                                   /~  Signature
                                                                       of
                                                                       Treasurer

         ---------------------------------------------------
     /~
         Signature of witness
         ---------------------------------------------------
     /~
         Name of witness (print)
</TABLE>

                                       3
<PAGE>


SCHEDULE 1: BUDGET - SFBR

         (a)      Item 1: Commencement Date July 1, 2005


ITEM 2: TOTAL BUDGET FOR THE PERIOD OF JULY 1, 2005 TO DECEMBER 31, 2005 IS
US$***, PAYABLE IN QUARTERLY PAYMENTS OF US$*** (DUE JULY 14, 2005) AND US$***
(OCTOBER 14, 2005).



<TABLE>
<CAPTION>
PERSONNEL:
<S>                       <C>                                <C>                <C>
John Blangero, Ph.D.                PI                        ***%              $***

Joanne Curran, Ph.D.                Co-I                      ***%              $***

Tom Dyer, Ph.D.            Co-I/Senior Prog.                  ***%              $***

Eric Moses, Ph.D.          Co-I                               ***%              $***

Tricia Curry                        Admin. Assistant          ***%              $***

Vicki Mattern                       Sr. Res. Assoc.           ***%              $***

                                                              TOTAL             US$***



SUPPLIES:
Computer supplies (cables, paper, printer supplies, miscellaneous software)     $***

Laboratory supplies  (complete 200 46K transcriptomic expression analyses)      $***

Communication  (phone, express mail, video conferencing)                        $***

                                                               TOTAL            US$***



EQUIPMENT:

Rack of 80 processor Opteron computers (for transcriptomic analyses)   US$***


TOTAL PERSONNEL, SUPPLIES AND EQUIPMENT:                               US$***
INDIRECT COSTS:                                                        US$***


GRAND TOTAL                                                            US$***
</TABLE>

                                       4
<PAGE>

Schedule 2: Project

                   CHEMGENEX CENTER FOR STATISTICAL GENOMICS:

                  SOUTHWEST FOUNDATION FOR BIOMEDICAL RESEARCH

         (b)      Research Aims:

1.       GENETIC AND TRANSCRIPTOMIC ANALYSIS OF CHEMGENEX GENES IN RELATION TO
         OBESITY/DIABETES.

     In order to validate the role of ChemGenex proprietary genes in relation to
     their role in obesity/diabetes, we will use transcriptional profiling to
     assess whether quantitative levels of these genes are correlated with both
     disease risk and other known correlates of disease risk.

     We will employ our novel methods of Bayesian analysis to find optimal
     predictors for the expression of each gene. This aim will be performed
     using extant data from the San Antonio Family Heart study families that
     ChemGenex/SFBR have been collaborating on for the previous two years and on
     additional gene expression profiles to be performed.


     TASKS:

         1)       To improve the power to identify gene expression-based
                  biomarkers, we will assay transcriptional profiles on an
                  additional 200 Mexican Americans. This will bring the total
                  number of profiles to a total of 1,200.


         2)       For each of up to 50 ChemGenex genes, we will examine whether
                  gene expression levels represent biomarkers for
                  diabetes/obesity risk by:

         a.       Testing whether gene expression levels are different (from the
                  population) in the first degree unaffected relatives of
                  individuals affected with either obesity or diabetes.

         b.       Testing the genetic correlation between expression levels of
                  ChemGenex genes and disease risk or with known quantitative
                  biomarkers of disease risk (such as fasting glucose levels and
                  BMI).

         This aim requires massive computational analysis using our novel
         Bayesian statistical analytical tools developed at SFBR which justifies
         the request for an additional 80 Opteron rack-mounted computer
         processors.


         3)       For each ChemGenex gene, we will conduct a genome-scan to
                  localize additional genetic factors influencing the
                  quantitative gene expression.

          MILESTONES: Completion of *** transcriptional profiles (by November
          2005). For each gene, the completion of tasks 2-3 will be considered a
          substantial milestone.

                                       5
<PAGE>


2.       GENETIC AND TRANSCRIPTOMIC ANALYSIS OF CHEMGENEX GENES IN RELATION TO
         DEPRESSION.



     In order to validate the role of ChemGenex proprietary genes in relation to
     their role in depression, we will use transcriptional profiling to assess
     whether quantitative levels of these genes are correlated with both disease
     risk and other known correlates of disease risk.

     We will employ our novel methods of Bayesian analysis to find optimal
     predictors for the expression of each gene. This aim will be performed
     using extant data from the San Antonio Family Heart study families that
     ChemGenex/SFBR have been collaborating on for the previous two years and on
     additional gene expression profiles to be performed.



         TASKS:

         1)       For each of up to 10 ChemGenex genes, we will examine whether
                  gene expression levels represent biomarkers for depression
                  risk by:

                  a.       Testing whether gene expression levels are different
                           (from the population) in the first degree unaffected
                           relatives of individuals affected with depression or
                           anxiety (as assessed by the use of specific medicines
                           for these conditions).

                  b.       Testing the genetic correlation between expression
                           levels of ChemGenex genes and disease risk or with
                           known quantitative biomarkers of disease risk (such
                           as BDNF plasma levels).

                  This aim requires massive computational analysis using our
                  novel Bayesian statistical analytical tools developed at SFBR.

         2)       For each ChemGenex gene, we will conduct a genome-scan to
                  localize additional genetic factors influencing the
                  quantitative gene expression.



MILESTONES: For each gene, the completion of tasks 1-2 will be considered a
substantial milestone.

                       __________________________________



3.       GENETIC AND TRANSCRIPTOMIC ANALYSIS OF CHEMGENEX GENES IN RELATION TO
         CANCER DRUG METABOLISM.



     In order to assess the genetic basis of response to cancer drugs, we will
     use transcriptional profiling to assess whether quantitative levels of drug
     metabolism genes (chosen as being of interest to ChemGenex) have
     substantial genetic components. This aim will be performed using extant
     data from the Mexican American families that ChemGenex/SFBR

                                       6
<PAGE>

     have been collaborating on for the previous two years and on additional
     gene expression profiles to be performed.



         TASKS:

         1)       For each of up to 5 genes chosen by ChemGenex, we will examine
                  whether gene expression levels correlates with any other
                  transcriptional product in the genome. This aim requires
                  massive computational analysis using our novel Bayesian
                  statistical analytical tools developed at SFBR.



         2)       For each gene, we will conduct a genome-scan to localize
                  additional genetic factors influencing the quantitative gene
                  expression.



         MILESTONES: For each gene, the completion of tasks 1-2 will be
         considered a substantial milestone.

                       __________________________________



4. STATISTICAL GENETIC ANALYSIS OF VARIANTS WITHIN CHEMGENEX GENES.



     We will continue our statistical genetic analyses of variants within
     positional candidate regions for diabetes/obesity including ***, ***, and
     ***. We will use Bayesian quantitative trait nucleotide analysis to test
     whether specific genes and gene variants are likely to be involved in the
     determination of quantitative phenotypes related to diabetes/obesity risk.
     This aim will continued to be performed using extant data from Mexican
     American families, MRCOB families, and Mauritian families than
     ChemGenex/SFBR have been collaborating on.



         TASKS:

         1)       For each set of genetic marker data (for the ***, ***, or ***
                  QTLs or any proprietary ChemGenex gene), we will perform
                  linkage disequilibrium analyses, marginal association
                  analyses, and Bayesian quantitative trait nucleotide analysis.



         MILESTONES: For each gene or marker set, the completion of tasks 1 will
         be considered a substantial milestone.

                                       7