Table 4.

Major limitations of genetic studies in PCOS.

Lack of universally accepted diagnostic criteria and definition	• NICHD criteria
	• Ultrasonographic criteria
	• Rotterdam criteria
Male phenotype?	• Premature baldness
	• Increased pilosity
	• Increased DHEAS levels?
	• Exaggerated responses to GnRH and ACTH
	• Insulin resistance, glucose intolerance
Relatively small sample size of the study populations	• Potential statistical error
Affected reproduction	• Difficulty in studying more than one generation
Nonrandom ascertainment of families	• Bias?
Obscurity in the mode of inheritance	• Autosomal Dominant [8, 12]
	• Monogenic [14, 17]
	• X-Linked [9, 10]
Variable penetrance and expressivity	• Difficulty in assignment of the phenotype
	(affected versus unaffected)
Locus heterogeneity	• Summarized in Section 4.
Environmental interactions	• Compensatory adaptation?