There are a lot of peculiar phobias out there, and pentheraphobia (fear of the mother-in-law) joins the more humorous ones that many people can probably relate to.
The word 'penthera' means mother-in-law in Greek, also worth noting is that phobia is also Greek, meaning fear.
It is considered a 'specific phobia,' which are fears of specific objects or situations, such as spiders, snakes, elevators, etc. These kinds of fears are typically not too invasive in one's life and many who suffer from a specific phobia continue to live a normal life.
Most phobias are caused by certain events, such as embarrassing or traumatic experiences. The likelihood of having a phobia can be increased by a person's hereditary predispositions or genetic make-up.
Depending on the severity of the phobia, a person who suffers from pentheraphobia may experience a variety of symptoms, including extreme anxiety, dread, panic, sweating, palpitations, nausea, shaking, and disruption of fluid speech.
If the condition is severe enough, there are treatments available, such as hypnotherapy, neuro-linguistic programming, and energy psychology.