Diversity in sex development

condtions where chromosomal, gonadal &/or anatomical sex characteristics development differently. Occurs in about 1/4500 births. DSDs = natural & diverse part of human bio.

Androgen Insensitivity Syndrome (AIS)

1/20,000 individuals
genetically male
mutation in gene responsible for producing androgen receptors → body unable to fully respond to androgen hormones (e.g. testosterone)
androgens = critical for dev of male traits
lack of responsiveness → complete/partial absence of male sex characteristics despite Y chromosome
2 main forms:

• Complete AIS (CAIS): individuals have external female genitalia & raises as girls. no internal female sex organs (e.g. uterus/ovaries), but they have descended testes. 1st apparent during adolescence - no menstruation

• Partial AIS (PAIS): mix of male/female physical characteristics. degree of insensitivity varies - different external genitalia in variation of people

Turner Syndrome (TS)

1/2000 individuals - genetically female
only one X chromosome, missing another → X0
45 chromosomes instead of 46

physical characteristics:
no menstrual cycle (amenorrhoea)
ovaries fail to develop
infertile
no breasts at puberty - broad chest
low set ears
wide ‘webbed’ neck
high waist-hip ratio (hips not much wider than waist)
childlike features retained in adulthood

psychological characteristics:
higher than avg reading ability
spatial, visual memory & mathematical tasks = lower than typical range
face challenges in social dev - hard to relate to peers same age

Klinefelter’s syndrome (KS)

1/650 individuals - genetically male
anatomical appearance of male
additional X chromosome - XXY
10% cases identified by prenatal diagnosis - often diagnosed accidentally during medical examination for unrelated condition
some individuals never aware of it

physical characteristics:
reduced body hair than non-KS male
breast dev at puberty
softening/rounding body contours at puberty
long, gangly limbs
underdeveloped genitals
coordination issues
susceptible to health problems more commonly found in females (e.g. breast cancer)

psychological characteristics:
KS linked to delayed dev in language skills & reading ability
passive & shy
lack interest in sexual acitivity
don’t respond well to stress
exhibit issues with ‘executive functions’ (e.g. memory / problem solving)

STRENGTH: nature/nurture debate

research contributed to N-N debate
compare DSD conditions to those without & identify psychological/behavioural differences
E.g. people with TS = higher verbal ability & tend to talk more than chromosome typical girls
logically inferred that behavioural differences = bio basis & result of less typical chromosome structure
support innate differences (nature) have powerful effect on gender

LIMITATION: counterpoint

issues in leaping to conclusion
relationship between atypical chromosomes associated with DSD conditions & differences in behaviour not solely due to biology
environmental & social influence= more responsible for behavioural influences
E.g. differences in social development seen in TS females → treated in childlike manner by people around them (result of youthful appearance) → encourages continuing childlike behaviour
not nature alone

STRENGTH: real world application

application of research → managing DSD conditions
E.g. CAIS people have increased risk for testicular cancer
Barros et al (2021): risk = very low in childhood → increases significantly in adulthood
knowledge allows clinicians to safely delay gonadectomy (testes removal) until after puberty - gonads can contribute hormones that support natural puberty, breast development & bone growth
early diagnosis -:> balance safety with hromone-driven development
enables safe management plan
increased awareness → useful real world app

LIMITATION: sampling issue

identify characteristics of DSD individuals → identify large number of individuals with (e.g. KS) → build a database
full range of characteristics mild→severe in database
mild symptoms tend not to be identified → picture of typical psychological symptoms distorted
Boada et al (2009): prospective studies following KS individuals from birth produced a more accurate picture of characteristics
Boada et al: many individuals KS - don’t experience significant congitive/psychological problems & many = highly successful academically & in personal lives
DSDs picture may be exaggerated