ITEM 7 EXHIBIT

RELEVANT SUBSIDIARIES OF PARENT HOLDING COMPANY

TCW Entities

Parent Holding Company:

The TCW Group, Inc.

Relevant Subsidiaries that are persons described in Rule 13d-1(b):

(i) TCW Asset Management Company LLC, a Delaware limited liability company and an Investment Adviser registered under Section 203 of the Investment Advisers Act of 1940.

This Schedule 13G is being filed by The TCW Group, Inc. (“TCW”) on behalf of itself and its direct and indirect subsidiaries, which collectively constitute The TCW Group, Inc. business unit (the “TCW Business Unit”). The TCW Business Unit is primarily engaged in the provision of investment management services. The TCW Business Unit is managed separately and operated independently.

Investment funds affiliated with The Carlyle Group, L.P. (“The Carlyle Group”) hold a minority indirect ownership interest in TCW that technically constitutes an indirect controlling interest in TCW. The principal business of The Carlyle Group is acting as a private investment firm with affiliated entities that include certain distinct specialized business units that are independently operated including the TCW Business Unit.

Entities affiliated with The Carlyle Group may be deemed to share beneficial ownership of the securities reported herein. Information barriers are in place between the TCW Business Unit and The Carlyle Group. Therefore, in accordance with Rule 13d-4 under the Exchange Act, The Carlyle Group disclaims beneficial ownership of the shares beneficially owned by the TCW Business Unit and reported herein. The TCW Business Unit disclaims beneficial ownership of any shares which may be owned or reported by The Carlyle Group and its affiliates.

Entities affiliated with The Carlyle Group may beneficially own shares of an issuer to which this schedule relates, and such shares are not reported herein.

SIGMATRON INTERNATIONAL INC SCHEDULE 13G