User::userUpdate

static function userUpdate($userFields)
    {
        if (array_key_exists('PERSONAL_BIRTHDAY', $userFields))
        {
            $date = new Date($userFields['PERSONAL_BIRTHDAY'], 'd.m.Y');
            $userFields['PERSONAL_BIRTHDAY'] = $date;
        }

	return BitrixRestApiUser::userUpdate($userFields);
    }