PSR J1953+1844 probably being the descendent of an Ultra-compact X-ray binary

PSR J1953+1844 (i.e. M71E) is a millisecond pulsar (MSP) in a 53-min binary orbit discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). It has an orbital period of 53 minutes and a mass function of $2.3\times10^{-7}$ M$_\odot$. The possible redback origin of this system has been discussed by Pan et al. (2023). We discuss here an alternative evolution track for this binary system as being a descendant of ultra-compact X-ray binaries (UCXBs), which has a hydrogen-poor donor accreting onto a neutron-star with an orbital period of $\leq1~hr$. Noticed that some of UCXB systems hold an accreting millisecond X-ray pulsars (AMXPs) and a $\sim$0.01 M$_\odot$ donor. M71E has a very similar orbit as AMXPs, indicating that it might be evolved from an UCXB as PSR J1653--0158. The companion star should be significantly bloated and it most probably has a carbon and oxygen composition, otherwise a low inclination angle is required for a helium companion. The discovery of this binary system may shed lights on when and how a NS in UCXBs turns to be a radio pulsar.