Genetics in obstetrics and gynecology / Joe Leigh Simpson [and others].

Date:
[1982], ©1982
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Genetics in obstetrics and gynecology / Joe Leigh Simpson [and others]. Source: Wellcome Collection.

    155/344 (page 141)
    COMMON GYNECOLOGIC DISORDERS / 143 Studies of inbred strains of mice suggest that heritable tendencies influence ovarian development. Ovarian w^eight, numbers of follicles per ovary, time at which estrus begins, ovarian response to gonadotropin, and rate of attrition of follicles relative to age differ between strains, implying genetic control. None of these variables have been studied genetically in humans. One factor that has been studied is the age of menarche. Social and en¬ vironmental factors complicate human studies, but several investigators have observed that the age of menarche differs less between monozygotic twins than between dizgotic twins (Petri, 1934; Tisserant-Perrier, 1953]. The age of men¬ arche also differs less among sisters than between unrelated women. The mag¬ nitude of the observed differences are consistent with the existence of polygenic or multifactorial factors. Knowledge of the age of menarche of relatives might permit a clinician to estimate an individual's age of menarche. Some investigators believe that the amount of blood lost each menstruation may be influenced by genetic factors (Rybo & Hallberg, 1966). Although a reasonable assumption, only this one study has been conducted and objections could be raised to its experimental design. The correlation between mother and daughter is better than that between unrelated individuals for length of cycle, regularity of menstruation, and presence of dysmenorrhea and premenstrual tension (Widholm & Kantero, 1971). In addition, menstrual abnormalities may result from genetically determined hematologic disorders. Menorrhagia or me¬ trorrhagia may be associated with deficiencies of clotting factors II, V, VII, and X, or with von Willebrand disease, an autosomal dominant trait in which the initial symptom may be excessive bleeding at surgery. Thrombopathie throm¬ bocytopenia (thrombasthenia) may also be associated with metrorrhagia or menorrhagia, although hemophilia (factor VIII deficiency) apparently is not. One might also predict that age of menopause would be more similar among sibs or near relatives than among the general population. However, we are aware of no formal studies. EXTERNAL GENITALIA In this section we shall discuss two relatively common conditions en¬ countered by gynecologists—imperforate hymen and fusion of the labia minora. Other disorders of sex differentiation associated with abnormal external gen¬ italia are considered in Chapter 10. Imperforate Hymen Ordinarily the central portion of the hymen is patent (perforate), thereby allowing outflow of mucus and blood. If the hymen is imperforate, mucus and blood accumulate in the vagina or uterus (hydrocolpos or hydrometrocolpos). An imperforate hymen is not particularly rare. Fortunately, the anomaly is easily corrected by surgical incisions, preferably cruciform. Mcllroy and Ward (1930) reported sibs who possibly had the disorder, but no other familial ag¬ gregates have been described.