Psychosexual conflicts, personality factors, and cultural beliefs are considered as being of etiological

significance to koro. Sexual adjustment histories of non-Chinese victims are often significant, such as premorbid sex inadequacy, sexual promiscuity, guilt over masturbation, and impotence.

When considering the biological mechanisms and evolutionary history of koro, it is important to look at it in the larger framework of mass hysteria. While the underlying mechanisms are still poorly understood, it has been suggested that the mirror neurons play a major role in mass hysteria outbreaks. Mirror neurons, which have been found in both human and non-human primates, are neurons that fire when one performs an action and when they observe another individual performing the same action. It is hypothesized that we evolved these mechanisms to learn from observation of others, as well as to facilitate imitation. However, within mirror neurons, there is some form of inhibitory process, which prevents us from blindly mimicking every action we observe others perform. New research into this area suggests that in mass hysteria outbreaks something goes amiss in this inhibitory process.

Until the 1970s, autism was rarely accepted to be a distinctive diagnosis, but, following changes to the Diagnostic and Statistical Manual of the American Psychiatric Association it is diagnosed much more often. How much of this increase is due to greater diagnostic vigilance by doctors, changes in diagnostic categories, or an actual increase in prevalence, remains unclear. Late-onset autism cases are estimated at 25% and reported by sources including the "British Medical Journal" as not having changed in recent years.

Despite others describing common bowel features, there have been no peer reviewed studies yet published, as of 2006, corroborating the existence of "autistic enterocolitis"; other studies have explicitly refuted its existence. Thus, it is not generally accepted that the types of colitis diagnosed in autistic individuals are either unique to autism, or more common in autistic people than in the general population.

Autistic enterocolitis is the name of a nonexistent medical condition proposed by discredited British gastroenterologist Andrew Wakefield when he suggested a link between a number of common clinical symptoms and signs which he contended were distinctive to autism. The existence of such an enterocolitis has been dismissed by experts as having "not been established". Wakefield's now-retracted and fraudulent report used inadequate controls and suppressed negative findings, and multiple attempts to replicate his results have been unsuccessful.

Reviews in the medical literature have found no link between the MMR vaccine and autism or with bowel disease.

Most of Wakefield's coauthors later retracted the conclusions of the original paper proposing the hypothesis, and the General Medical Council found Wakefield guilty of manipulating patient data and misreporting results. His work has been exposed as falsified and described as an "elaborate fraud".

There is not enough known about persistent genital arousal disorder to definitively pinpoint a cause. Medical professionals think it is caused by an irregularity in sensory nerves, and note that the disorder has a tendency to strike post-menopausal women, or those who have undergone hormonal treatment.

Some drugs such as trazodone may cause priapism as a side effect, in which case discontinuing the medication may give relief. Additionally, the condition can sometimes start only after the discontinuation of SSRIs. In some recorded cases, the syndrome was caused by or can cause a pelvic arterial-venous malformation with arterial branches to the penis or clitoris; surgical treatment was effective in this case.

In other situations where the cause is unknown or less easily treatable, the symptoms can sometimes be reduced by the use of antidepressants, antiandrogenic agents, and anaesthetising gels. Psychotherapy with cognitive reframing of the arousal as a healthy response may also be used.

More recently, the symptoms of the condition have also been linked with pudendal nerve entrapment. Regional nerve blocks and less common surgical intervention have demonstrated varying degrees of success in most cases. There is, however, no evidence for the long-term efficacy of surgical intervention.

In one recent case, serendipitous relief of symptoms was noted from treatment with varenicline, a treatment for nicotine addiction.

The condition is sometimes classified as a psychiatric disorder. However, it can also be caused by medical problems such as diabetic neuropathy, multiple sclerosis, genital mutilation, complications from genital surgery, pelvic trauma (such as from a straddle injury caused by falling on the bars of a climbing frame, bicycle or gymnastics beam), hormonal imbalances, total hysterectomy, spinal cord injury, cauda equina syndrome, uterine embolisation, childbirth trauma (vaginal tearing through the use of forceps or suction or a large or unclosed episiotomy), vulvodynia and cardiovascular disease.

A common cause of situational anorgasmia, in both men and women, is the use of anti-depressants, particularly selective serotonin reuptake inhibitors (SSRIs). Though reporting of anorgasmia as a side effect of SSRIs is not precise, studies have found that 17–41% of users of such medications are affected by some form of sexual dysfunction.

Another cause of anorgasmia is opiate addiction, particularly to heroin.

About 15% of women report difficulties with orgasm, and as many as 10% of women in the United States have never climaxed. Only 29% of women always have orgasms with their partner.

Secondary anorgasmia is close to 50% among males undergoing prostatectomy; 80% among radical prostatectomies. This is a serious adverse result because radical prostatectomies are usually given to younger males who are expected to live more than 10 years. At more advanced ages, the prostate is less likely to grow during that person's remaining lifetime. This is generally caused by damage to the primary nerves serving the penile area, which pass near the prostate gland. Removal of the prostate frequently damages or even completely removes these nerves, making sexual response unreasonably difficult.

A number of medical reports of phimosis incidence have been published over the years. They vary widely because of the difficulties of distinguishing physiological phimosis (developmental nonretractility) from pathological phimosis, definitional differences, ascertainment problems, and the multiple additional influences on post-neonatal circumcision rates in cultures where most newborn males are circumcised. A commonly cited incidence statistic for pathological phimosis is 1% of uncircumcised males. When phimosis is simply equated with nonretractility of the foreskin after age 3 years, considerably higher incidence rates have been reported.

Others have described incidences in adolescents and adults as high as 50%, though it is likely that many cases of physiological phimosis or partial nonretractility were included.

The most acute complication is paraphimosis. In this condition, the glans is swollen and painful, and the foreskin is immobilized by the swelling in a partially retracted position. The proximal penis is flaccid. Some studies found phimosis to be a risk factor for urinary retention and carcinoma of the penis.

A retrospective postal survey of 396 men found that 4% had significant genital pain for more than one year that required surgical intervention.

Another study contacted 470 vasectomy patients and received 182 responses, finding that 18.7% of respondents experienced chronic genital pain with 2.2% of respondents experiencing pain that adversely affected quality of life.

The most robust study of post-vasectomy pain, according to the American Urology Association's Vasectomy Guidelines 2012 (amended 2015) found a rate of 14.7% reported new-onset scrotal pain at 7 months after vasectomy with 0.9% describing the pain as "quite severe and noticeably affecting their quality of life".

Gonadectomy at time of diagnosis is the current recommendation for PAIS if presenting with cryptorchidism, due to the high (50%) risk of germ cell malignancy. The risk of malignancy when testes are located intrascrotally is unknown; the current recommendation is to biopsy the testes at puberty, allowing investigation of at least 30 seminiferous tubules, with diagnosis preferably based on OCT3/4 immunohistochemistry, followed by regular examinations. Hormone replacement therapy is required after gonadectomy, and should be modulated over time to replicate the hormone levels naturally present in the body during the various stages of puberty. Artificially induced puberty results in the same, normal development of secondary sexual characteristics, growth spurt, and bone mineral accumulation. Women with PAIS may have a tendency towards bone mineralization deficiency, although this increase is thought to be less than is typically seen in CAIS, and is similarly managed.

In medicine, Infantilism is an obsolete term for various, often unrelated disorders of human development, up to developmental disability, which consist of retention of the physical and/or psychological characteristics of early developmental stages (infant, child) into a relatively advanced age.

Various types of infantilism were recognized, lumped together in the above superficial description. With better understanding of the endocrine system and genetic disorders, various disorders which included the word "infantilism" received other names. For example, Brissaud's infantilism, described by Édouard Brissaud in 1907 is now known as myxedema (a form of hypothyroidism); "intestinal infantilism" of Christian Archibald Herter is called coeliac disease. The Turner syndrome was described as "a syndrome of infantilism" by Henry Turner himself.

Terms such as "genital infantilism" (infantilism in development of genitals, hypogenitalism), or "sexual infantilism" (lack of sexual development after expected puberty or delayed puberty) may still be seen, and are considered to be synonyms of hypogonadism. "Somatic infantilism" refers to infantilism of overall bodily development. Speech infantilism is a speech disorder.

Similarly to some other medical terms (cretinism, idiotism), "infantilism"/"infantile" may be used pejoratively (synonymous to "immature").

Depending on phenotypic features, impotence and other sexual problems such as anejaculation or sexual aversion may be fairly common among individuals with PAIS, but do not necessarily indicate low libido. Support groups for individuals with PAIS may help affected individuals discuss their concerns more comfortably. Some individuals with PAIS may try to avoid intimate relationships out of fear of rejection; individual therapy may help some to overcome social anxiety, and restore focus to interpersonal relationships instead of solely on sexual function and activity.

Clitoromegaly is a rare condition and can be either present by birth or acquired later in life.

If present at birth, congenital adrenal hyperplasia can be one of the causes, since in this condition the adrenal gland of the female fetus produces additional androgens and the newborn baby has ambiguous genitalia which are not clearly male or female. In pregnant women who received norethisterone during pregnancy, masculinization of the fetus occurs, resulting in hypertrophy of the clitoris; however, this is rarely seen nowadays due to use of safer progestogens. It can also be caused by the autosomal recessive congenital disorder known as Fraser syndrome.

In acquired clitoromegaly, the main cause is endocrine hormonal imbalance affecting the adult woman, including polycystic ovarian syndrome (PCOS) and hyperthecosis. Acquired clitoromegaly may also be caused by pathologies affecting the ovaries and other endocrine glands. These pathologies may include virulent (such as arrhenoblastoma) and neurofibromatosic tumors. Another cause is clitoral cysts. Sometimes there may be no obvious clinical or hormonal reason.

Female bodybuilders and athletes who use androgens, primarily to enhance muscular growth, strength and appearance , may also experience clearly evident enlargement of the clitoris and increases in libido. Women who use testosterone for therapeutic reasons (treating low libido, averting osteoporosis, as part of an anti-depressant regimen, etc.) experience some enlargement of the clitoris, although the dosages warranted for these conditions are much lower. Pseudoclitoromegaly or pseudohypertrophy of the clitoris "has been reported in small girls due to masturbation: manipulations of the skin of prepuce leads to repeated mechanical trauma, which expands the prepuce and labia minora, thus imitating true clitoral enlargement".

In "Atlas of Human Sex Anatomy (1949)" by Robert Latou Dickinson, the "typical" clitoris is defined as having a crosswise width of 3 to 4 mm (0.12 - 0.16 inches) and a lengthwise width of 4 to 5 mm (0.16 - 0.20 inches). On the other hand, in Obstetrics and Gynecology medical literature, a frequent definition of clitoromegaly is when there is a clitoral index (product of lengthwise and crosswise widths) of greater than 35 mm (0.05 inches), which is almost twice the size given above for an "average" sized clitoral hood.

Frenulum breve may be complicated by tearing of the frenulum during sexual or other activity and is a cause of dyspareunia. It may lead to erroneous labelling of the sufferer as having psychosexual problems. The torn frenulum may result in healing with scar tissue that is less flexible after the incident causing further difficulties. However, this tearing can also solve the problem, healing such that the frenulum is longer and therefore no longer problematic. The diagnosis of frenulum breve is almost always confused with that of phimosis and a generally tight foreskin, since the symptom is difficulty retracting the foreskin. Most men with phimosis also have frenulum breve to a certain extent.

XX male syndrome is a rare congenital condition where an individual with a female genotype has phenotypically male characteristics that can vary between cases. In 90% of these individuals the syndrome is caused by unequal crossing over between X and Y chromosomes during meiosis in the father, and results in the X chromosome containing the SRY gene, as opposed to the Y chromosome where it is normally found. When the X with the SRY gene combines with a normal X from the mother during fertilization, the result is an XX male. Less common are SRY-negative XX males which can be caused by a mutation in an autosomal or X chromosomal gene. The masculinization of XX males is variable.

This syndrome is diagnosed through various detection methods and occurs in approximately 1:20 000 newborn males, making it less common than Klinefelter syndrome. Treatment is medically unnecessary, although some individuals choose to undergo treatments to make them appear more male or female. It is also called de la Chapelle syndrome, for Albert de la Chapelle, who characterized it in 1972.

Frenulum breve, or short frenulum, is a condition in which the frenulum of the penis, which is an elastic band of tissue under the glans penis that connects to the foreskin and helps contract it over the glans, is too short and thus restricts the movement of the foreskin. The frenulum should normally be sufficiently long and supple to allow for the full retraction of the foreskin so that it lies smoothly back on the shaft of the erect penis.

The penile frenulum is comparable to the tongue's frenulum between the tongue's lower surface and the lower jaw, or the frenulum between the upper lip and the outside of the upper gum.

The degree to which individuals with XX male syndrome develop the male phenotype is variable, even among SRY-positive individuals. A completely male phenotype usually develops in the presence of the SRY gene but, in some cases, the presence of the SRY gene can result in internal and/or external genitalia ambiguities. Normal XX females undergo X inactivation during which one copy of the X chromosome is silenced. It is thought that X inactivation in XX males may account for the genital ambiguities and incomplete masculinization seen in SRY-positive XX males. The X chromosome with the SRY gene is preferentially chosen to be the active X chromosome 90% of the time, which is why a complete male phenotype is often seen in SRY-positive XX males. In the remaining 10%, X inactivation spreads to include a portion of the SRY gene, resulting in incomplete masculinization.

Masculinization of SRY-negative XX males is dependent upon which genes have mutations and at what point in development these mutations occur.

Michelin tire baby syndrome (also known as "Folded skin with scarring"), is characterized by multiple, symmetric, circular skin creases, or bands, on the forearms, lower legs, and often the neck that are present at birth. The creases disappear later in life. But it is a dangerous skin disease as it resides in the body rest of life, it can lead to death. They are reminiscent of those of Bibendum, the mascot of the tire manufacturer, Michelin, hence the name of the syndrome. Associated abnormalities vary and may include facial dysmorphism, upslanting palpebral fissures, hypertelorism, cleft palate, genital anomalies, mild developmental delay, ureterocele, smooth muscle hamartoma, nevus lipomatosus, Laron syndrome (dwarfism with high growth hormone and low somatomedin activity), and other defects.

It was originally described by Ross in 1969.

Twenty cases of this disorder have been reported.

Any of the aforementioned pain conditions/syndromes can persist for years after vasectomy and affect as many as one in three vasectomized men. The range of PVPS pain can be mild/annoying to the less-likely extreme debilitating pain experienced by a smaller number of sufferers in this group. There is a continuum of pain severity between these two extremes. Pain is thought to be caused by any of the following, either singularly or in combination: testicular backpressure, overfull epididymides, chronic inflammation, fibrosis, sperm granulomas, and nerve entrapment. Pain can be present continuously in the form of orchialgia and/or congestive epididymitis or it can be situational, such as pain during intercourse, ejaculation or physical exertion.

Estimates for the incidence of androgen insensitivity syndrome are based on a relatively small population size, thus are known to be imprecise. CAIS is estimated to occur in one of every 20,400 46,XY births. A nationwide survey in the Netherlands based on patients with genetic confirmation of the diagnosis estimates that the minimal incidence of CAIS is one in 99,000. The incidence of PAIS is estimated to be one in 130,000. Due to its subtle presentation, MAIS is not typically investigated except in the case of male infertility, thus its true prevalence is unknown.

Depending on the mutation, a person with a 46,XY karyotype and AIS can have either a male (MAIS) or female (CAIS) phenotype, or may have genitalia that are only partially masculinized (PAIS). The gonads are testes regardless of phenotype due to the influence of the Y chromosome. A 46,XY female, thus, does not have ovaries or a uterus, and can neither contribute an egg towards conception nor gestate a child.

Several case studies of fertile 46,XY males with AIS have been published, although this group is thought to be a minority. Additionally, some infertile males with MAIS have been able to conceive children after increasing their sperm count through the use of supplementary testosterone. A genetic male conceived by a man with AIS would not receive his father's X chromosome, thus would neither inherit nor carry the gene for the syndrome. A genetic female conceived in such a way would receive her father's X chromosome, thus would become a carrier.

Lichen sclerosus may have a genetic component. Higher rates of lichen sclerosus have been reported among twins and among family members.