revenue recognized in 2019 was primarily the recognition of proceeds from the NeoGenomics arbitration. As of December 31, 2019, the Company had no deferred revenue. Total deferred revenue was $18,077, $61,465 and $104,853 at December 31, 2018, 2017 and 2016, respectively.
Operating and Other Expenses
Amortization expense, which is the amortization of costs of acquiring or filing of patents over their estimated useful lives, was $262,719 for each of the years ended December 31, 2018, 2017 and 2016. For the year ended December 31, 2019 amortization expense was $152,908.
Professional and consulting fees totaled $83,735 for 2019 compared with $59,456 for 2018, $126,799 for 2017 and $213,977 for 2016. These fees consist primarily of patent filing and maintenance costs, consulting fees, and accounting fees.
Legal fees totaled $86,997 during the year ended December 31, 2019, compared with $10,359 during the same period 2018, $72,020 in 2017 and $32,458 in 2016. The increase in legal fees in 2019 was a result of costs associated with the Company’s response to the patent interference proceedings.
Research and development fees were $0 during 2019, 2018 and 2017 and $27,000 during 2016. The research and development fees were related primarily to fees paid to consultants relating to the development work completed as a part of our NeoGenomics License.
Compensation expense totaled $371,690 for the year ended December 31, 2019, $285,421 in 2018, $308,631 for 2017 and $282,195 for 2016. The increase in 2019 was due to a one-time compensation paid to directors for their efforts in the success of the NeoGenomics and Intel matters.
Other general and administrative expenses totaled $754,024 in 2019, $195,965 in 2018, $134,382 in 2017, and $179,308 in 2016. The 2019 increase in other general and administrative expense was due to the non-cash expense of option awards.
Other Income and Expense
The Company received a total payment of $6.6 million as a result of the NeoGenomics arbitration ruling. $1.5 million of the arbitration award was attributed to “milestone and royalty payments”, with the remaining $5.1 million attributed to punitive damages. Hence, the Company reported $5.1 million as other income for the period ending December 31, 2019.
Other income was immaterial for the year ended December 31, 2018. For the year ended December 31, 2017, the unrealized loss on NeoGenomics stock held at the end of the reporting period was $13,077. For the period ending December 31, 2016, the company recorded other income of $82,138 as a result of realizing a gain on NeoGenomics stock in the amount of $12,395 along with a $69,743 gain on payables restructuring.
Other expense for the year ended December 31, 2019 totaled $3.7 million, primarily as a result of litigation related fees. Other expense totaled $25,854 for 2018 and $1,210 for 2017 as a result of interest expense. For the year ended December 31, 2016 other expense totaled $1.2 million resulting from a change in warrants liability. As previously disclosed, the Company had issued options and warrants which exceeded the amount of common shares available if the holders exercised all of the previously issued outstanding options and warrants. This created a common stock warrant liability for the Company. During the first quarter of 2016, based upon the trading price of the Company’s common stock, this liability increased to $940,812 and during the second quarter of 2016 increased to $1,196,612. At the Annual Shareholder Meeting of the Company held on May 17, 2016, the shareholders approved an increase to the authorized shares of common and preferred stock. As a result, on May 17, 2016 common stock warrant liability for the Company was eliminated.
Liquidity and Capital Resources
At December 31, 2019, the Company had $2.3 million in cash and total current liabilities of $884,897. The primary amount of current liabilities relates to $206,637 in dividends payable, $440,089 in accrued wages and $200,000 in convertible debt. As a result, we will have sufficient resources to meet all of our current obligations. The Company is pursuing licensing activity and collaborations to increase revenue. Additionally,