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Androgen insensitivity syndrome (AIS) (Epidemiology (Commonest form of…
Androgen insensitivity
syndrome (AIS)
Definition
Gynaecological disorder where a genetically male
individual has a female phenotype due to
mutation in the androgen receptor
Epidemiology
Commonest form of undermasculinisation in XY
Commonly X-linked (2/3) or de novo (1/3)
Rare
Pathophysiology
Genetics
X-linked mutation in androgen receptor gene,
causing resistance to androgens in target tissues
46XY male develops female external genital organs
Embryological development
Testes develop normally in the embryo but Wolffian structures do not (testosterone dependent);
AMH is secreted so Mullerian structures regress
Phenotype
Varied; Can be complete or partial (CAIS or PAIS)
Female external genitalia with short blind-ending vagina
Internal testes (found as inguinal hernias/labial swellings)
Absent internal female genital organs (uterus, ovaries, tubes)
Normal breasts, sparse axillary and pubic hair
Clinical
presentation
Inguinal hernias/labial swelling
Primary amenorrhoea
(delayed menarche)
Prenatally (XY vs USS)
Diagnosis
Examination
Pelvic
Sparse pubic hair
Female external genitalia
Short, blind ending vagina
Impalpable uterus
General
Normal breast development
Sparse axillary hair
Investigations
Imaging
Pelvic USS (locate testes, exclude mullerian structures)
Bloods
Karyotyping (XY)
History
Management
Medical
HRT
Indication: post-gonadectomy
MOA: replaces female hormones
Testosterone
Indication: add on to help feel better
Surgical
Gonadectomy
Indication: after puberty
MOA: removes intra-abdominal testes,
reducing malignancy risk
Conservative
Information and advice
Psychologist and support groups
If before puberty, conservative to allow natural puberty