The incidence of familial cases of premature ovarian failure varies from 4 to 31%. Recall bias may explain part of the variance. Thorough evaluation of alleged affected relatives showed a lower incidence than the original family history suggested. In the present study the incidence of familial cases was 12.7%. Pedigree studies on affected families showed a mode of inheritance suggestive of autosomal dominant sex-limited transmission or X-linked inheritance with incomplete penetrance. An adequate family history can distinguish between familial or sporadic premature ovarian failure. The risk of female relatives developing premature ovarian failure may be as high as 100% in familial premature ovarian failure, or as low as 1% in sporadic cases.

Fragile X premutations are considered to be a risk factor for premature ovarian failure (POF), which is usually defined as menopause at age <40 years. Since premutations may be inherited from either the mother or the father, we evaluated the influence of the inheritance pattern on the duration of reproductive life in female carriers. The occurrence of POF and age at menopause in women with a paternally inherited fragile X premutation (PIP) were compared to those in women with a maternally inherited fragile X premutation (MIP). We identified 148 women in whom the parental origin of the premutation could be determined. In 109 of these women we were able to establish whether POF had occurred: 82 women had a PIP, and 27 had a MIP. Twenty-three of the women (28%) with a PIP had POF, versus only 1 (3.7%) with a MIP (two -tailed Fisher's exact test; P=. 007). Kaplan-Meier analysis of all 148 premutations showed that the age at menopause was significantly lower in the women with a PIP than in the woman with a MIP (Breslow test in Kaplan-Meier analysis; P=.003). Our data strongly suggest that, when POF occurs in fragile X premutation carriers, a considerable proportion of the premutations are inherited paternally (parent-of-origin effect). We hypothesize that this may be owing to a paternal genomic imprinting effect.

Fragile X premutations are known to be a risk factor for diminished ovarian function at a relatively young age. We studied endocrine profiles of female fragile X family members (n = 79) at risk of premature ovarian failure (POF). Of these 79 women aged <40 years, 45 had menstrual cycles, and 34 were using oral contraceptives. Of the women with menstrual cycles, the premutation carriers had higher serum FSH concentrations than women who were not carrying the premutation. Even premutation carriers with regular cycles showed increased serum FSH concentrations. Moreover, premutation carriers using oral contraceptives also demonstrated increased serum FSH concentrations. Irrespective of whether oral contraceptives were used, a serum FSH concentration of > or =15 IU/l was more common in the premutation carriers than in the other women. One premutation carrier using oral contraceptives had a serum FSH concentration of >40 IU/l, the threshold that defines POF. We confirmed that premutation carriers with menstrual cycles demonstrate premature ovarian dysfunction. However, we also found endocrine signs of unrecognized ovarian dysfunction in premutation carriers using oral contraceptives, despite endocrine alterations by oral contraceptives. Premutation carriers may have a poorer prognosis for future pregnancy, either achieved spontaneously or by assisted reproductive technology. We recommend that premutation carriers should be counselled not to wait too long if they wish to start a family.

Carriers of fragile X premutations were previously considered phenotypically normal but are now known to be at risk for premature ovarian failure (POF). This prompted us to investigate whether premutation carriers (PC) have an increased risk for other diseases. We approached 306 women out of 84 fra(X) families of whom 264 (86.3%) participated in this study. A medical history was taken of these women. Whenever possible, the anamnestic data were verified with medical records. We first evaluated the occurrence of diseases that are commonly associated with menopause in PC and compared this to that in women with either a normal FMR-1 gene or a full mutation. We found no statistically significant differences in the occurrence of diseases known to be associated with menopause, such as cardiovascular diseases and osteoporosis. However, lower bone mineral density was observed only in PC. Subsequently, we compared the occurrence of other medical problems between the two groups by estimating relative risks. PC did not demonstrate other diseases more commonly compared to non-PC from the same families. These findings are important for the counseling of PC. Carriership of the premutation may affect the ovaries, but does not substantially increase the risk for additional medical problems. Once a PC does experience POF, she is at risk for early estrogen deprivation, which may lead to a premature decrease in bone density, when not treated.

Imprinting effect in premature ovarian failure confined to paternally inherited fragile X premutations. Am J Hum Genet 66:413-418 Morton NE, Macpherson JN (1992) Population genetics of the fragile-X syndrome: multiallelic model for the FMR1 locus.