REVISED FIRST AMENDMENT TO LEASE

Exhibit 10.20

REVISED FIRST AMENDMENT TO LEASE

This REVISED First Amendment to Lease (the “First Amendment”), is made and entered into this 12TH day of APRIL, 2012 by and between Mission West Properties, L.P., a Delaware limited partnership (“Lessor”) and Ariosa Diagnostics, Inc., a Delaware Corporation (“Lessee”).

RECITALS

A. Lessee has entered into a lease with Lessor for an approximately 23,994 square foot building located at 0000 Xxxxxxx Xxxxx, Xxx Xxxx, Xxxxxxxxxx (the “Premises”) dated June 10, 2011 (the “Lease”).

B. Lessee has agreed to lease an additional 1669 sq. ft. of shell space.

NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which are acknowledged, the parties hereto agree to amend the Lease as follows:

1. Premises: Lessee has leased an addition 1669 sq. ft. for a total of 25,663 sq. ft. and 38% of building.

2. BASIC RENT: The basic rent shall be adjusted to and payable as follows:

		Basic Rent*				CAC**				Total
February 1, 2012 – July 31, 2012		$	44,908			$	6,359			$	51,267

* Monthly base rent to increase by $.05 per sq. ft. over prior year’s monthly base rent on the annual anniversary of the Commencement Date each year during the Lease Term over the prior year’s monthly base rent starting on August 1, 2012 to $1.80 or $46,193.

3. FIRST RIGHT OF REFUSAL: Lessor hereby grants Lessee a first right of refusal to lease any space available on ground floor of Building @5941-45 Optical, the 2^nd Floor of 5941 Optical if Biotech Center closes in the future, and 5961 Optical. If 5961 has been leased, then 5901 and 5921 Optical subject to other first rights of refusal.

4. RATIFICATION OF LEASE: Except as modified herein, the Lease is hereby ratified, approved and confirmed upon all the terms, covenants, and conditions.

5. AUTHORITY: Each party executing this First Amendment represents and warrants that he or she is duly authorized to execute and deliver this First Amendment. If executed on behalf of a corporation, that this First Amendment is executed in accordance with the by-laws of said corporation for a partnership that this First Amendment is executed in accordance with the partnership agreement of such partnership, that no other party’s approval or consent to such execution and delivery is required, and that this First Amendment is binding upon said individual, corporation (or partnership) as the case may be in accordance with its terms.

INTENTIONALLY BLANK

1.

IN WITNESS WHEREOF, the parties have executed this First Amendment, by their duly authorized signatories as of the day first above written.

Lessor Mission West Properties L.P. By: Mission West Properties, Inc., Its General Partner						Lessee ARIOSA DIAGNOSTICS, INC.
By:		/s/ Xxxx X. Xxxx				By:		/s/ Xxx Song
Print Name:		Xxxx X. Xxxx				Print Name:		Xxx Song
Title:		CEO				Title:		CEO
Date: 4/11/12						Date: 4/12/12

2.