Androgen Insensitivity Syndrome (AIS) is caused by mutations in the androgen receptor gene located on the X chromosome. There are three main types - complete AIS, partial AIS, and mild AIS - which vary in their phenotypic expression. Treatment depends on the type of AIS and may include gonadectomy, hormone replacement therapy, and counseling. Two case studies presented a family pedigree analysis showing phenotypic variation between individuals with the same mutation, and a patient with partial AIS who responded well to high dose testosterone therapy despite having a mutation in the androgen receptor binding domain.

1. Androgen Insensitivity
Syndrome
By; Stefan Dennis & Rachel Lammers

2. Outline
● Introduction: Types of AIS
● Production of Endogenous Testosterone
● Genetic Overview
● Mechanisms: pathophysiology
● Development
● Treatment
● BPA: An EDC of the Androgen Receptor
● Two Case studies
○ Phenotype of AIS in family pedigrees
○ Treatment for PAIS with hormone replacement therapy
● Conclusion

3. What is Androgen Insensitivity Syndrome?
● X linked mutation in the
androgen receptor gene
● Mothers will pass on to children
50% of the time
● Daughters are carriers but do
not express
● Affected sons are genetically
male and phenotypically female

4. Three Types
● Absent wolffian duct derivatives
● Absence or presence of
epididymides and/or vas deferens
● Abdominal testes
● Short blind-ending vagina
● Limited or absent pubic and/or
axillary hair
Complete Androgen Insensitivity
(CAIS)
Grade 7

5. Three Types
Predominantly Female
Grade 5 and 6
● clitoralmegaly
(enlarged clitoris)
● fusion of the labia
● pubic hair growth at
puberty
Predominantly Male
Grade 2 and 3
● micropenis
● Cryptorchidism
(absence of one or
both testes)
● perineal hypospadias
Ambiguous
Grade 4
● descended or
undescended testes
● half way between male
and female genetalia
Partial Androgen Insensitivity
(PAIS)

6. ● Impaired spermatogenesis and/or impaired pubertal virilization
● Infertility
● Gynecomastia in puberty
● Higher voice
Three Types
Mild Androgen Insensitivity (MAIS)
Grade 1

7. Synthesis and Secretion of Testosterone
● In men, LH stimulates production of:
- testosterone by the Leydig cells in
the testis
- androgen-binding protein (ABP)
by the Sertoli cells of the testis
● Testosterone is the main androgen
hormone responsible for male sexual
development

8. The AR Gene: Genetic overview
● A single copy gene
● Chromosome X at Xq11-12
● Spans ~90kb of genomic DNA
● Protein coding region is
comprised of 8 exons ( ~2757bp)
● Exon 1: amino-terminal domain
CAG repeats on the 5' end, of
NTD. Highly polymorphic and
found to expand in infertile men.
● Exon 2-3 :DNA binding domain
● Exon 4-8 (3'): ligand-binding
domain.
● Exon 4' 5' region encodes the
hinge region.
AR Protein is compose of a NTD;N-terminal
domain, DBD: DNA-binding domain, Hinge
region, and LBD: Ligand binding domain.

9. Mechanism of Action
N-Terminal Domain: Involved in the regulation of
target gene transcription
via protein-protein interactions.
DNA-Binding Domain: Consists of two zinc clusters
involved in P box binding. Dimerization and
interaction with DNA is determined by stability.
Ligand Binding Domain: High affinity binding of
androgen, mediating the movement of AR from the
cytoplasm into the nucleus.
Hinge region: mediates the AR targeting signal and
movement from the cytoplasm to its nuclear site of
action

10. Pathophysiology
Impairment of normal receptor
mediated transcription causes
pathogenicity through three distinct
mechanisms.
1. Virilization: The development
of sexual differences.
2. Masculinization: The
development of both primary and
secondary male characteristics.
3. Anabolism: The inability to
generate larger molecules and
compounds necessary for signalling
and gene transcription.

11. Fetal Development vs. Puberty
In developing embryo and fetus:
● At 9 weeks: testes secrete androgens.
● Between 11 and 18 weeks: Testosterone peaks stimulates differentiation of the
Wolffian duct system into epididymis, vas deferens and seminal
● Vesicles, followed by prostate development and external genitalia.
At puberty:
● Menstruation doesn’t occur
● Testosterone levels are high BUT
● Lack of male secondary hair characteristics
● No change in voice

12. Treatment/Intervention
Treatment of AIS can include:
● General Treatment based on correct
diagnosis
● Difficult and complicated decision due
to socio-economic implications
● Surgery: gonadectomy
● Hormone replacement
● Counseling
Specific Cases:
1. PAIS: testosterone treatment: promote
virilization (male characteristics) of
external genitalia before sex assignment.
2. CAIS: XY individuals having normal
female external genitalia:
-Individuals raised as females
-Prepubertal gonadectomy
-Estrogen replacement therapy
-Vaginal length requires dilatation
-Psychological support of the family
3. MAIS: promoting spermatogenesis and
fertility in a man with MAIS
Testosterone Enanthate can be used for
hormone replacement therapy in PAIS

13. BPA: An EDC of the Androgen Receptor
Thermoplastic are plastic materials which
become pliable above specific temperatures
and will solidify upon cooling.
● Reshaping parts in various ways with
the use of molding/bending
Bisphenol A (BPA) is a precursor molecule for
the creation of many polycarbonate plastics.
appears in a wide range of:
● Flame-retardants
● Dental sealants
● Plastic products
● Food packaging since the 1960s
In a 2008 study of adult males ages 18-71,
90% of urine samples were found to have
BPA metabolites
Recent studies have soon BPA has multiple
effects on many endocrine related signalling
pathways; including both the estrogen and
androgen pathways.
● positive association between BPA
excretion in urine and the expression
of two estrogen-responsive genes,
ESR2 (ERβ) and ESRRA (ERRα )
● However... It also functions as an
antagonist for the androgen receptor;
decreasing transcription rates through
competitive competition of the AR
More research into the effects of estrogen
as a antagonist to normal DNA
transcription must be conducted.

14. Case Study 1:
Genotype Versus Phenotype in Families with Androgen Insensitivity Syndrome
Methods:
49 patients with possible AIS were identified and family histories
were obtained for the past 3-4 generations.
DNA was isolated from the genital skin fibroblasts and did a PCR to
screen the AR gene for mutations.
Results:
In 32 patients there was an AR gene mutations and 19 (59%) had
affected relatives.
Family K-Patient 8 was raised as a girl until the age of 2 upon finding
inguinal testes and the sex was changed to a male. Underwent many
corrective surgical procedures for his genitalia along with hormone
replacement therapy.
Family N- 2 individuals affected by PAIS but both had a very different
phenotype. One raised as a girl who was not detected until age 13 and the
other raised as a boy because of a micropinus and scrotum with testes
Phenotypic variation was absent in families with CAIS, distinctly present in
families with PAIS and as a result, sex assignment at birth of an individual with
PAIS cannot be based on a specific AR gene mutation

15. Case Study 2:
Response to Androgen Treatment in a Patient with PAIS
Subject: A 23 year old man who sought medical attention at 19 for undervirilization.
- He had no acne, no beard growth, high pitch voice, mild breast development,
penis size of 5.5cm, and no erections or fantasies.
Methods: Performed analysis of genital skin fibroblasts from biopsies, androgen
receptor binding, and androgen receptor DNA
-Started a high dose of testosterone treatment (250mg testosterone
enanthate weekly by injections at age 19 till 23)
Results: Slight decrease in androgen binding capacity. PCR and DNA sequencing
showed a mutation in the second zinc finger of the binding domain at exon 3
leading to a change of an arginine to a glutamine in codon 607.
-First response of the treatment was detected after 6 months, and after 3.5 years he developed beard growth,
secondary male sex hair characteristics and a deepened voice. His penile size increased to 7.5cm, libido became
normal and breast size decreased
This was one of the first cases to see an improvement of virilization in a patient with PAIS and a mutation in the binding
domain of the receptor. There is no general parameter to predict the best treatment for someone with PAIS as it depends on
the case, but this study showed that a high dose testosterone therapy may be successful.

16. Conclusion
● The three degrees of androgen insensitivity vary largely
in phenotypic expression due to the specific nature of
the mutation.
● Genetic variation may contribute to the polymorphism
of the N-terminus; facilitating AR defectiveness.
● Detection at birth and puberty are the most powerful
indicators of AR; allowing for more effective treatment.
● EDC such as BPA are proven to act as both E2 agonist
and testosterone antagonist….so limit your intake.

17. Questions: Short Answer
List the three types of the Androgen Insensitivity Syndrome (3
marks). For one of the types, give two phenotypic
characteristics (2 marks).
Complete Androgen Insensitivity (CAIS), Partial Androgen Insensitivity (PAIS) and Mild
Androgen Insensitivity (MAIS).
Phenotypic Characteristics Include:
CAIS- Phenotypically a female so will have a blind ending vagina, clitoris, high-pitched voice and
breast development
PAIS- Phenotype can vary tremendously but if predominantly a female will have a clitoris, blind-
ending vagina and public hair. Predominantly a male will have a micropenis and may have one or
two testis. Ambiguous patients may have a mix of these characteristics.
MAIS-Phenotypically a male so will have testes and gynecomastia (breast development)

18. Questions: Multiple Choice
2. Which of the following is NOT a viable
treatment of complete androgen insensitivity?
a. Gonadectomy
b. Hormone replacement therapy
(testosterone)
c. Hormone replacement therapy (estrogen)
d. Therapy
e. None of the above
1.Which portion of the AR gene allows for its
translocation into the nucleus through nuclear
pores?
a. N- Terminus Domain
b. DNA-Binding Domain
c. Hinge Region
d. Ligand-Binding Domain
e. Intron 4

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