The researchers theorised that either of the following situations could be antecedents to necrophilia:
The necrophiliac develops poor self-esteem, perhaps due in part to a significant loss;
(a) They are very fearful of rejection by others and they desire a sexual partner who is incapable of rejecting them; and/or
(b) They are fearful of the dead, and transform their fear—by means of reaction formation—into a desire. They develop an exciting fantasy of sex with a corpse, sometimes after exposure to a corpse. Motives
The most common motive for necrophiliacs is the possession of a partner who is unable to resist or reject them. However, in the past, necrophiliacs have expressed having more than one motive.The authors reported that of their sample of 34 genuine necrophiliacs:
68% were motivated by a desire for a non-resisting and non-rejecting partner
21% were motivated by a want for a reunion with a lost partner
15% were motivated by sexual attraction to dead people
15% were motivated by a desire for comfort or to overcome feelings of isolation
12% were motivated by a desire to remedy low self-esteem by expressing power over a corpseLesser common motives include:

Unavailability of a living partner
Compensation for a fear of women
Belief that sex with a living woman is a mortal sin
Need to achieve a feeling of total control over a sexual partner
Compliance with a command hallucination
Performance of a series of destructive acts
Expression of polymorphous perverse sexual desires
Need to perform limitless sexual activityIQ data was limited, but not abnormally low. About half of the sample had a personality disorder, and 11% of true necrophiliacs were psychotic.
Differential diagnosis
The symptoms of Legius syndrome and NF-1 are very similar; An important difference between Legius syndrome and NF-1 is the absence of tumor growths Lisch nodules and neurofibromas which are common in NF-1.A genetic test is often the only way to make sure a person has LS and not NF-1; the similarity of symptoms stem from the fact that the different genes affected in the two syndromes code for proteins that carry out a similar task in the same reaction pathway. Treatment
Management of Legius syndrome is done via the following:
Physical therapy
Speech therapy
Pharmacologic therapy (e.g. methylphenidate for ADHD)The prognosis of this condition is generally considered good with appropriate treatment. See also
List of cutaneous conditions
List of genes mutated in cutaneous conditions

References
Further reading
MD, Robert P. Erickson; PhD, Anthony J. Wynshaw-Boris MD (2016). Epsteins Inborn Errors of Development: The Molecular Basis of Clinical Disorders of Morphogenesis. Oxford University Press. ISBN 9780190275426. Retrieved 1 June 2017. Zhang, Jia (2016). "Molecular screening strategies for NF1-like syndromes with café-au-lait macules". Molecular Medicine Reports. 14 (5): 4023–4029. doi:10.3892/mmr.2016.5760. PMC 5112360. PMID 27666661. Review

External links
PubMed