Acceptance of fragile X premutation genetic screening in women with ovarian dysfunction

Longitudinal interviews of couples diagnosed with diminished ovarian reserve undergoing fragile X premutation testing

About 10 % of infertile/subfertile women are diagnosed with diminished ovarian reserve (DOR), of which < 5 % will become pregnant spontaneously. Fragile X (FMR1) genetic testing may provide a reason for her early ovarian aging and/or have reproductive implications. Seven women with DOR (genetic study subset) and the male partners of six of these women were separately interviewed about the experience of being asked to undergo this unanticipated genetic test. Three interviews were conducted (before, within 1 week after, and 3 months after learning the test results). None of the participants carried the FMR1 premutation (largest FMR1 allele 27-50 CGG repeats). For women, their pregnancy-seeking journey was long and exhausting. Women understood the reproductive implications of carrying the FMR1 premutation, and hoped for a negative result. Being offered a genetic test caused women to pause and re-think their future reproductive plans. Husbands viewed the infertility journey as filled with unknowns, of which the genetic test results would be one more puzzle piece. The expense of fertility testing/treatment was mentioned by both spouses, though more notably by husbands. The introduction of a possible genetic cause of infertility, with additional potential health consequences for future biological children, caused women to re-think their quest for pregnancy. In contrast, the genetic test was viewed as an additional source of information for their husbands as opposed to raising concern regarding potential reproductive ramifications.

"It's about having the choice": stakeholder perceptions of population-based genetic carrier screening for fragile X syndrome

This project explored, the views of key stakeholders regarding population-based genetic carrier screening for fragile X syndrome (FXS). Interviews and focus groups were conducted with healthcare providers, relatives of individuals with FXS and members of the general population. Data were transcribed verbatim and coded into themes. 188 individuals took part in this study. Perceived benefits of carrier screening included: learning the risk of having a child with FXS; learning the risk of fragile X-associated primary ovarian insufficiency; and the opportunity for carriers to access reproductive options. Concerns included: the emotional impact of screening and receiving a carrier result; the predictive testing nature of the carrier test with respect to fragile X-associated tremor/ataxia syndrome; potential confusion created by receiving an intermediate result; and implications of genetic screening for society. Overall, population-based genetic carrier screening was perceived to be acceptable provided it is optional and offered at an appropriate stage of life. With the support of the participants to promote individual choice by offering a population-based carrier screening program for FXS, it is essential to carefully consider how screening might be offered in order to ensure broad accessibility and facilitation of decision-making.

Fragile X syndrome: the FMR1 CGG repeat distribution among world populations

Fragile X syndrome (FXS) is characterized by moderate to severe intellectual disability, which is accompanied by macroorchidism and distinct facial morphology. FXS is caused by the expansion of the CGG trinucleotide repeat in the 5' untranslated region of the fragile X mental retardation 1 (FMR1) gene. The syndrome has been studied in ethnically diverse populations around the world and has been extensively characterized in several populations. Similar to other trinucleotide expansion disorders, the gene-specific instability of FMR1 is not accompanied by genomic instability. Currently we do not have a comprehensive understanding of the molecular underpinnings of gene-specific instability associated with tandem repeats. Molecular evidence from in vitro experiments and animal models supports several pathways for gene-specific trinucleotide repeat expansion. However, whether the mechanisms reported from other systems contribute to trinucleotide repeat expansion in humans is not clear. To understand how repeat instability in humans could occur, the CGG repeat expansion is explored through molecular analysis and population studies which characterized CGG repeat alleles of FMR1. Finally, the review discusses the relevance of these studies in understanding the mechanism of trinucleotide repeat expansion in FXS.

Caregiver opinions about fragile X population screening

PURPOSE

We sought to determine caregiver perceptions about population screening for fragile X and to examine factors potentially associated with support for screening.

METHODS

We asked 1,099 caregivers of a child with fragile X syndrome or a fragile X carrier to rate whether free, voluntary screening should be offered preconception, prenatally, neonatally, or when problems occur. Caregivers chose a preferred time for screening, reported whether screening would affect parent-child bonding, indicated preferences for carrier detection, and gave reasons for their choices.

RESULTS

Caregivers endorsed all forms of screening, but prenatal screening was less strongly endorsed than preconception or postnatal screening. Most (79%) preferred preconception carrier testing, allowing more options when making reproductive decisions. Most thought that screening should also disclose carrier status and believed a positive screen would not negatively affect parent-child bonding. Maternal education, caregiver depression, family impact, and severity of disability were not associated with screening opinions, but parents who only had carrier children were less likely to endorse prenatal screening.

CONCLUSION

Caregivers of children with fragile X widely endorse screening. However, because different parents will make different choices, screening may need to be offered at multiple times with careful consideration of consent and informed decision-making.

A molecular and cytogenetic investigation of FMR1 gene premutations in Polish patients with primary ovarian insufficiency

OBJECTIVE

The aim of this study was to determine the prevalence of premutations in the FMR1 gene that cause primary ovarian insufficiency (POI) in a group of affected women.

STUDY DESIGN

Forty DNA samples were purified from peripheral blood collected from women with ovarian failure who were under 40 years of age. A routine cytogenetic test was performed to eliminate chromosomal aberrations as the cause of POI. The DNA was analysed by polymerase chain reaction (PCR) with primers specific to the FMR1 gene region. The PCR products were then separated in denaturing polyacrylamide gels using an ABI Prism 377 sequencer.

RESULTS

Cytogenetic analysis of the samples revealed two X/autosome translocations. DNA analysis identified FMR1 gene premutations in three patients. The frequency of X/autosome translocations in the studied group was 2/40 (5.0%), and the frequency of FMR1 gene premutations was 3/38 cases (7.9%). Thus, genetic tests allowed for the identification of POI in five (12.5%) out of 40 women.

CONCLUSION

FMR1 gene premutation is a common genetic cause of POI.

Genetic evaluation of oocyte donors: recipient couple preferences and outcome of testing

OBJECTIVE

To report preferences of recipient couples for genetic testing of their oocyte donors.

DESIGN

Observational report of results from a genetic testing-options form implemented as part of routine care.

SETTING

Private practice.

PATIENT(S)

Recipients and oocyte donors.

INTERVENTION(S)

Recipient couples completed a form before screening of their oocyte donor that outlined required screening and recommended tests that the couple could accept or decline. Couples were given information about carrier frequency, risk to their child if results were abnormal, and cost.

MAIN OUTCOME MEASURE(S)

Percentage of couples accepting optional testing.

RESULT(S)

Of the 63 couples with data available from their first testing-options form, 42 (67%) accepted and 21 (33%) declined fragile X testing, whereas 34 (54%) accepted and 29 (46%) declined karyotyping. When asked whether they would accept additional testing of their donor if it was recommended by a genetic counselor, 15 (24%) said that they would accept additional testing regardless of cost, 35 (56%) declined, and 13 (20%) indicated that their decision would depend on the cost. In many cases, history was elicited by the genetic counselor or test results were obtained that influenced further testing, decisions to proceed, or provided information important for the child.

CONCLUSION(S)

Recipient couples sometimes chose to decline tests that we recommended but did not require, despite the relatively low cost of this testing compared with the total cost of the oocyte donation cycle.