Genetic Counseling and Testing for FMR1 Gene Mutations: Practice Guidelines of the National Society of Genetic Counselors

Parent perspectives following newborn screening resulting in diagnoses of fragile X syndrome or fragile X premutation

BACKGROUND

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Early Check, a voluntary newborn screening study, screened 18,833 newborns for FXS over ∼3 years. Exploring parental attitudes and perspectives can provide insight to the potential future acceptability of public health screening.

METHODS AND PROCEDURES

Mothers of infants who received a screen positive result for FXS (n = 6) or fragile X premutation (FXPM; n = 18) were interviewed about their perceptions and experiences.

OUTCOMES AND RESULTS

Mothers of children with FXS described utility in receiving information about their child, particularly to monitor for potential developmental issues and intervene early; overall mothers did not regret participating. Mothers reported various reactions to receiving the FXS or FXPM results including (1) stress and worry; (2) guilt; (3) sadness and disappointment; (4) neutrality, relief, and acceptance; and (5) confusion and uncertainty.

CONCLUSIONS AND IMPLICATIONS

Despite initial reactions such as sadness, stress, and worry, mothers found value in learning of their child's presymptomatic diagnosis of FXS, particularly the anticipated long-term benefits of early diagnosis to their child's health and wellbeing. Our results indicate that professionals returning positive newborn screening results should anticipate and prepare for reactions such as parental shock, guilt, sadness, and uncertainty. Genetic counseling and psychosocial support are critical to supporting families.

Insight and Recommendations for Fragile X-Premutation-Associated Conditions from the Fifth International Conference on FMR1 Premutation

The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.

Prenatal diagnosis after high chance non-invasive prenatal testing for trisomies 21, 18 and 13, chorionic villus sampling or amniocentesis? - Experience at a district general hospital in the United Kingdom

The non-invasive prenatal testing (NIPT) analyses cell-free DNA (cfDNA) derived from the placental tissue in the maternal circulation. Though highly sensitive and specific, a major limitation is in cases of confined placental mosaicism (CPM). Whether to perform chorionic villus sampling (CVS) or amniocentesis to confirm a positive NIPT result is controversial. One major drawback of CVS is that cytogenetic diagnosis may not always reflect the true chromosomal make-up of the fetus. This work, therefore, proposes the use of amniocentesis in the presence of normal ultrasound findings, and the option of either CVS or amniocentesis when there are abnormal USS findings.

Fragile X Syndrome in children

Fragile X syndrome is caused by the expansion of CGG triplets in the FMR1 gene, which generates epigenetic changes that silence its expression. The absence of the protein coded by this gene, FMRP, causes cellular dysfunction, leading to impaired brain development and functional abnormalities. The physical and neurologic manifestations of the disease appear early in life and may suggest the diagnosis. However, it must be confirmed by molecular tests. It affects multiple areas of daily living and greatly burdens the affected individuals and their families. Fragile X syndrome is the most common monogenic cause of intellectual disability and autism spectrum disorder; the diagnosis should be suspected in every patient with neurodevelopmental delay. Early interventions could improve the functional prognosis of patients with Fragile X syndrome, significantly impacting their quality of life and daily functioning. Therefore, healthcare for children with Fragile X syndrome should include a multidisciplinary approach.

The diagnostic experience of women with fragile X-associated primary ovarian insufficiency (FXPOI)

PURPOSE

The fragile X premutation occurs when there are 55-200 CGG repeats in the 5' UTR of the FMR1 gene. An estimated 1 in 148 women carry a premutation, with 20-30% of these individuals at risk for fragile X-associated primary ovarian insufficiency (FXPOI). Diagnostic experiences of FXPOI have not previously been included in the literature, limiting insight on experiences surrounding the diagnosis. This study identifies barriers and facilitators to receiving a FXPOI diagnosis and follow-up care, which can inform care and possibly improve quality of life.

METHODS

We conducted qualitative interviews with 24 women with FXPOI exploring how FMR1 screening, physician education, and supportive care impacted their experience. Three subgroups were compared: women diagnosed through family history who have biological children, women diagnosed through family history who do not have biological children, and women diagnosed through symptoms of POI.

RESULTS

Themes from interviews included hopes for broader clinician awareness of FXPOI, clear guidelines for clinical treatment, and proper fertility workups to expand reproductive options prior to POI onset. Participants also spoke of difficulty finding centralized sources of care.

CONCLUSIONS

Our results indicate a lack of optimal care of women with a premutation particularly with respect to FMR1 screening for molecular diagnosis, short- and long-term centralized treatment, and clinical and emotional support. The creation of a "FXPOI health navigator" could serve as a centralized resource for the premutation patient population, assisting in connection to optimal treatment and appropriate referrals, including genetic counseling, mental health resources, advocacy organizations, and better-informed physicians.

Fragile X premutation carrier screening in Pakistani preconception women in primary care consultation

Purpose

Women of reproductive age who carry fragile X premutation (PM) alleles have 56 to 200 CGG repeats in the 5′-untranslated region of FMR1 gene are at increased risk for producing children with intellectual disabilities (ID) or autism spectrum disorders (ASD) due to expansion of PM alleles to full mutation alleles (> 200 repeats) during maternal transmission.

Methods

In present study fragile X PM carrier screening was performed in total 808 women who were consulting primary health care centers for preconception care in Khyber Pakhtunkhwa region of Pakistan between April, 2018 and December, 2020. Polymerase chain reaction (PCR) was performed for detection of PM carrier women and the CGG repeats number was confirmed by Southern blotting and capillary electrophoresis.

Results

The prevalence rate for PM carriers among preconception women was found to be 0.7% that was contributed by 0.5% women in risk group (RG1) with family history of ID and 0.2% in risk group 2 (RG2) with family history of ASD. PM carrier women had at least one affected child or sibling. In addition, the preconception women with FMR1 PM alleles were found to be at increased risk for primary ovary insufficiency (RG1: P = 0.0265, RG2: P = 0.0389), postpartum depression (RG1: P = 0.0240, RG2: P = 0.0501) and neuropsychiatric disorders (RG1: P = 0.0389, RG2: P = 0.0432).

Conclusions

Current study provides first evidence of fragile X PM carrier screening in Pakistani preconception women in primary care consultation. Findings of current study may help to improve preconception care and to reduce burden of fragile X associated disorders in our population.

A cross-sectional survey of genetic counselors providing carrier screening regarding GBA variants and Parkinson disease susceptibility

PURPOSE

Adult-onset disease risks associated with carriers of recessive disease have and will continue to be identified. As carrier screening becomes more broadly utilized, providers face the dilemma of whether they should discuss these risks during discussions with prospective parents. This study aimed to understand whether preconception/prenatal genetic counselors (PPGCs) were aware of the risk of Parkinson disease in carriers of, and persons with, Gaucher disease and the reasons behind choosing whether to discuss this risk with patients.

METHODS

Eligible participants included board-certified or board-eligible genetic counselors who had counseled preconception/prenatal patients within the past 3 years. An online survey was distributed via the National Society of Genetic Counselors in November of 2017.

RESULTS

One hundred twenty genetic counselors completed the quantitative survey, distributed in Fall of 2017. While the majority of respondents knew of the Gaucher-related Parkinson's link (n = 78; 65%), just over one-third reported discussing it in preconception/prenatal settings (n = 30; 38.5%). Respondents reported discussing these links more consistently when disclosing positive results or when the patient/family approached the topic. Respondents cited the lack of professional guidelines as one of the main reasons for not discussing the link.

CONCLUSION

These results highlight an inconsistency in PPGCs' discussions of the Parkinson's risk in Gaucher disease carriers, and the need to develop guidelines regarding these issues to help standardize the care and education of patients.

High-Throughput Methylation-Specific Triplet-Primed PCR and Melting Curve Analysis for Selective and Reliable Identification of Actionable FMR1 Genotypes

Methylated FMR1 full-mutation expansions cause fragile X syndrome. FMR1 premutation carriers are susceptible to other late-onset conditions, and women with premutation are at risk of transmitting a fully expanded FMR1 allele to offspring. Identification of individuals with actionable FMR1 genotypes (full-mutation males and females, and premutation females at risk for primary ovarian insufficiency and/or having fragile X-affected offspring) can enable timely access to intervention services and genetic counseling. This study presents a rapid, first-tier test based on melting curve analysis of methylation-specific triplet-primed PCR amplicons (msTP-PCR MCA) for concurrent detection of FMR1 CGG-repeat expansions and their methylation status. The msTP-PCR MCA assay was optimized on 20 fragile X reference samples, and its performance was evaluated on 111 peripheral blood-derived DNA samples from patients who have undergone prior molecular testing with PCR and/or Southern blot analysis. The msTP-PCR MCA assay detected all samples with a methylated FMR1 CGG-repeat expansion, and had sensitivity, specificity, positive predictive value, and negative predictive values of 100%, 92.06%, 91.1%, and 100%, respectively. The msTP-PCR MCA assay identified premutation/full-mutation mosaicism down to 1%, detected skewed inactivation in females with FMR1 expansions, and enabled selective identification of all individuals with an actionable FMR1 genotype. The msTP-PCR MCA assay may aid in fragile X screening of at-risk populations and newborns and voluntary carrier screening of women of reproductive age.

Refining reproductive risk for FMR1 premutation carriers in the general obstetric population

Female FMR1 premutation (FMR1 PM) carriers for fragile X syndrome (FXS) are at risk to have a child with FXS based on their CGG repeat size and AGG interruption number. Studies examining this risk in unselected populations of female PM carriers are lacking. This retrospective cohort study analyzed carrier status, CGG repeat length, AGG interruption result, and reproductive risk refinement in a population of female patients who underwent routine carrier screening for FXS. A total of 1536 PM carriers (0.43%) were identified, 95% of whom had between 55 and 90 CGG repeats. A number of 1334 carriers underwent AGG interruption testing. The majority had at least one AGG interruption and received a lower reproductive risk for FXS following AGG interruption testing (89% and 85%, respectively) as compared to their risk calculated based on CGG repeat size alone. The average change in risk across the population following AGG interruption testing was -3.4%, with a range from -50.8% to 48.9%. This article describes the range of CGG repeats and AGG interruptions in an unselected population of female PM carriers and suggests that most carriers would benefit from AGG interruption testing to refine their reproductive risk of having a child with FXS.

Defining the Critical Components of Informed Consent for Genetic Testing

Purpose: Informed consent for genetic testing has historically been acquired during pretest genetic counseling, without specific guidance defining which core concepts are required. Methods: The Clinical Genome Resource (ClinGen) Consent and Disclosure Recommendations Workgroup (CADRe) used an expert consensus process to identify the core concepts essential to consent for clinical genetic testing. A literature review identified 77 concepts that are included in informed consent for genetic tests. Twenty-five experts (9 medical geneticists, 8 genetic counselors, and 9 bioethicists) completed two rounds of surveys ranking concepts’ importance to informed consent. Results: The most highly ranked concepts included: (1) genetic testing is voluntary; (2) why is the test recommended and what does it test for?; (3) what results will be returned and to whom?; (4) are there other types of potential results, and what choices exist?; (5) how will the prognosis and management be impacted by results?; (6) what is the potential family impact?; (7) what are the test limitations and next steps?; and (8) potential risk of genetic discrimination and legal protections. Conclusion: Defining the core concepts necessary for informed consent for genetic testing provides a foundation for quality patient care across a variety of healthcare providers and clinical indications.

Laboratory testing for fragile X, 2021 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG)

Molecular genetic testing of the FMR1 gene is commonly performed in clinical laboratories. Pathogenic variants in the FMR1 gene are associated with fragile X syndrome, fragile X-associated tremor ataxia syndrome (FXTAS), and fragile X-associated primary ovarian insufficiency (FXPOI). This document provides updated information regarding FMR1 pathogenic variants, including prevalence, genotype-phenotype correlations, and variant nomenclature. Methodological considerations are provided for Southern blot analysis and polymerase chain reaction (PCR) amplification of FMR1, including triplet repeat-primed and methylation-specific PCR.The American College of Medical Genetics and Genomics (ACMG) Laboratory Quality Assurance Committee has the mission of maintaining high technical standards for the performance and interpretation of genetic tests. In part, this is accomplished by the publication of the document ACMG Technical Standards for Clinical Genetics Laboratories, which is now maintained online ( http://www.acmg.net ). This subcommittee also reviews the outcome of national proficiency testing in the genetics area and may choose to focus on specific diseases or methodologies in response to those results. Accordingly, the subcommittee selected fragile X syndrome to be the first topic in a series of supplemental sections, recognizing that it is one of the most frequently ordered genetic tests and that it has many alternative methods with different strengths and weaknesses. This document is the fourth update to the original standards and guidelines for fragile X testing that were published in 2001, with revisions in 2005 and 2013, respectively.This versionClarifies the clinical features associated with different FMRI variants (Section 2.3)Discusses important reporting considerations (Section 3.3.1.3)Provides updates on technology (Section 4.1).

Development of Chinese genetic reference panel for Fragile X Syndrome and its application to the screen of 10,000 Chinese pregnant women and women planning pregnancy

Background

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability caused by a CGG repeat expansion in the 5′ untranslated region of the FMR1 gene. When the number of repeats exceeds 200, the gene becomes hypermethylated and is transcriptionally silenced, resulting in FXS. Other allelic forms of the gene that are studied because of their instability or phenotypic consequence include intermediate alleles (45–54 CGG repeats) and premutation alleles (55–200 repeats). Normal alleles are classified as having <45 CGG repeats. Population screening studies have been conducted among American and Australian populations; however, large population‐based studies have not been completed in China.

Methods and Results

In this work we present FXS screening results from 10,145 women of childbearing age from China. We first created and tested a standard panel that was comprised of normal, intermediate, premutation, and full mutation samples, and we performed the screening after confirming the consistency of genotyping results among laboratories.

Conclusion

Based on our findings, we have determined the intermediate and premutation carrier prevalence of 1/130 and 1/634, respectively, among Chinese women.

Fragile X syndrome carrier screening accompanied by genetic consultation has clinical utility in populations beyond those recommended by guidelines

Background

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability. Many providers offer preconception or prenatal FXS carrier screening. However, guidelines recommend screening only for those with a family history or undergoing fertility evaluation. Wider screening has been resisted because of concerns about patient understanding of FXS‐associated inheritance patterns and phenotypes. Additionally, the clinical utility has been questioned.

Methods

We addressed these concerns by analyzing reproductive decision‐making and pregnancy management informed by post‐test genetic consultation among 122 FMR1 premutation carriers identified by expanded carrier screening.

Results

Sixty‐three percent of those screened met guidelines screening criteria; the remaining 37% did not. Ninety‐eight percent had undergone post‐test genetic consultation. Of respondents screened preconceptionally, 74% reported planning or pursuing actions to reduce the risk of an affected pregnancy; the extent to which couples planned/pursued these actions was not significantly different between those meeting either screening criterion (76%) versus those meeting neither criterion (55%). Of respondents screened prenatally, 41% pursued prenatal diagnostic testing; the extent to which couples pursued prenatal diagnosis was not significantly different between those who met either screening criterion (37%) versus those who met neither criterion (31%).

Conclusion

These results support the expansion of FXS screening criteria in guidelines.

The prevalence of CGG repeat expansion mutation in FMR1 gene in the northern Chinese women of reproductive age

BACKGROUND

The prevalence of CGG repeat expansion mutation in FMR1 gene varies among different populations. In this study, we investigated the prevalence of this mutation in women of reproductive age from northern China.

METHODS

A total of 11,891 pre-conceptional or pregnant women, including 5037 pregnant women and 7357 women with the history of spontaneous abortion or induced abortion due to delayed growth of the embryos, were recruited. The number of CGG repeats in FMR1 was measured by the TRP-PCR method. We also offered genetic counseling and prenatal diagnosis to the women carrying pre-mutation or full mutation alleles.

RESULTS

The prevalence of pre-mutation in reproductive women in northern China was 1/410, higher than that in southern China and Korea but lower than that in western countries. We also found that the prevalence of pre-mutation was relatively high (1/320) in women with abortion history.

CONCLUSION

Screening for CGG repeat expansion mutation in FMR1 should be recommended to the women with the history of spontaneous abortion or induced abortion due to delayed growth of the embryos.

Absence of AGG Interruptions Is a Risk Factor for Full Mutation Expansion Among Israeli FMR1 Premutation Carriers

Introduction: Fragile X syndrome (FXS) is a common form of X-linked intellectual and developmental disability with a prevalence of 1/4000-5000 in males and 1/6000-8000 in females. Most cases of the syndrome result from expansion of a premutation (55-200 CGGs) to a full mutation (>200 CGGs) repeat located in the 5' untranslated region of the fragile X mental retardation (FMR1) gene. The risk for full mutation expansions increases dramatically with increasing numbers of CGG repeats. Recent studies, however, revealed AGG interruptions within the repeat area function as a "protective factor" decreasing the risk of intergenerational expansion. Materials and Methods: This study was conducted to validate the relevance of AGG analysis for the ethnically diverse Israeli population. To increase the accuracy of our results, we combined results from Israel with those from the New York State Institute for Basic Research in Developmental Disabilities (IBR). To the best of our knowledge this is the largest cohort of different ethnicities to examine risks of unstable transmissions and full mutation expansions among FMR1 premutation carriers. Results: The combined data included 1471 transmissions of maternal premutation alleles: 369 (25.1%) stable and 1,102 (74.9%) unstable transmissions. Full mutation expansions were identified in 20.6% (303/1471) of transmissions. A total of 97.4% (388/397) of transmissions from alleles with no AGGs were unstable, 79.6% (513/644) in alleles with 1 AGG and 46.7% (201/430) in alleles with 2 or more AGGs. The same trend was seen with full mutation expansions where 40% (159/397) of alleles with no AGGs expanded to a full mutation, 20.2% (130/644) for alleles with 1 AGG and only 3.2% (14/430) in alleles with 2 AGGs or more. None of the alleles with 3 or more AGGs expanded to full mutations. Conclusion: We recommend that risk estimates for FMR1 premutation carriers be based on AGG interruptions as well as repeat size in Israel and worldwide.

FMR1 premutation frequency in a large, ethnically diverse population referred for carrier testing

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and is caused by an expansion of cytosine‐guanine‐guanine (CGG) repeats in the FMR1 gene. Female premutation allele carriers (55–200 CGG repeats) are at risk to have an affected child. Currently, specific population‐based carrier screening for FXS is not recommended. Previous studies exploring female premutation carrier frequency have been limited by size or ethnicity. This retrospective study provides a pan‐ethnic estimate of the Fragile X premutation carrier frequency in a large, ethnically diverse population of women referred for routine carrier screening during a specified time period at Progenity, Inc. Patient ethnicity was self‐reported and categorized as: African American, Ashkenazi Jewish, Asian, Caucasian, Hispanic, Native American, Other/Mixed/Unknown, or Sephardic Jewish. FXS test results were stratified by ethnicity and repeat allele category. Total premutation carrier frequency was calculated and compared against each ethnic group. A total of 134,933 samples were included. The pan‐ethnic premutation carrier frequency was 1 in 201. Only the Asian group differed significantly from this frequency. Using the carrier frequency of 1 in 201, a conservative pan‐ethnic risk estimate for a male fetus to have FXS can be calculated as 1 in 2,412. This risk is similar to the highest ethnic‐based fetal risks for cystic fibrosis and spinal muscular atrophy, for which population‐wide screening is currently recommended. This study adds to the literature and supports further evaluation into specific population‐wide screening recommendations for FXS.

Fragile X-Associated Diminished Ovarian Reserve and Primary Ovarian Insufficiency from Molecular Mechanisms to Clinical Manifestations

Fragile X syndrome (FXS), is caused by a loss-of-function mutation in the FMR1 gene located on the X-chromosome, which leads to the most common cause of inherited intellectual disability in males and the leading single-gene defect associated with autism. A full mutation (FM) is represented by more than 200 CGG repeats within the FMR1 gene, resulting in FXS. A FM is inherited from women carrying a FM or a premutation (PM; 55–200 CGG repeats) allele. PM is associated with phenotypes distinct from those associated with FM. Some manifestations of the PM are unique; fragile-X-associated tremor/ataxia syndrome (FXTAS), and fragile-X-associated primary ovarian insufficiency (FXPOI), while others tend to be non-specific such as intellectual disability. In addition, women carrying a PM may suffer from subfertility or infertility. There is a need to elucidate whether the impairment of ovarian function found in PM carriers arises during the primordial germ cell (PGC) development stage, or due to a rapidly diminishing oocyte pool throughout life or even both. Due to the possibility of expansion into a FM in the next generation, and other ramifications, carrying a PM can have an enormous impact on one’s life; therefore, preconception counseling for couples carrying the PM is of paramount importance. In this review, we will elaborate on the clinical manifestations in female PM carriers and propose the definition of fragile-X-associated diminished ovarian reserve (FXDOR), then we will review recent scientific findings regarding possible mechanisms leading to FXDOR and FXPOI. Lastly, we will discuss counseling, preventative measures and interventions available for women carrying a PM regarding different aspects of their reproductive life, fertility treatment, pregnancy, prenatal testing, contraception and fertility preservation options.

Informed decision making and psychosocial outcomes in pregnant and nonpregnant women offered population fragile X carrier screening

PurposePopulation-based carrier screening for fragile X syndrome (FXS) is still not universally endorsed by professional organizations due to concerns around genetic counseling for complex information and potential for psychosocial harms.MethodsWe determined uptake levels, decision making, and psychosocial impact in a prospective study of pregnant and nonpregnant Australian women offered FXS carrier screening in clinical settings. Women received pretest genetic counseling, and completed questionnaires when deciding and one month later.ResultsOf 1,156 women recruited, 83.1% returned the first questionnaire with 70.6% nonpregnant and 58.8% pregnant women choosing testing (χ²=16.98, P<0.001). Overall, informed choice was high in both nonpregnant (77.4%) and pregnant (72.9%) women (χ²=0.21, P=0.644), and more tested (76.0%) than not-tested (66.7%) women (χ²=6.35, P=0.012) made an informed choice. Measures of depression, stress, and anxiety were similar to population norms for ~85% of women. Decisional conflict and regret were generally low; however, decisional uncertainty and regret were greater in pregnant than nonpregnant women, and not-tested than tested women (uncertainty: χ²=18.51, P<0.001 and χ²=43.11, P<0.001, respectively; regret: χ²=6.61, P<0.037 and χ²=35.54, P<0.001, respectively).ConclusionWe provide evidence to inform guidelines that population FXS carrier screening can be implemented with minimal psychosocial harms following appropriate information and prescreening genetic counseling.

Preconception and prenatal genetic counselling

Identifying individuals at risk of having children affected by genetic conditions or congenital anomalies allows counselling that aims to inform reproductive decisions. This process takes place either at the preconception or early prenatal stage, although more options are available if risks are identified before the pregnancy. Preconception counselling covers issues that can affect the health of the mother and baby including folic acid supplementation. Carrier screening for autosomal recessive diseases, such as beta thalassaemia, has resulted in a significantly reduced incidence in many countries. National organisations, however, advocate more in-depth research before such screening recommendations apply to the general population. Recently, advances in genomic technologies have made it possible to greatly expand the scope of genetic screening, with the aim of providing more comprehensive information to prospective parents. This is a complex field, and research should focus on how the technology can be put to best use in the future.

Prognostic dilemmas and genetic counseling for prenatally detected fragile X gene expansions

With widespread adoption of fragile X carrier screening in pregnant women, the number of expectant couples receiving news of an unanticipated Fragile X Mental Retardation 1 (FMR1) gene expansion has increased. The most common abnormal result from maternal FMR1 testing involves an intermediate allele, also known as a gray zone result, which requires genetic counseling but poses minimal risk for an adverse developmental outcome. By contrast, the finding of a maternal FMR1 premutation or full mutation during pregnancy has important implications for the woman herself, her unborn child, and her extended family. These multiple levels of impact, in addition to the complex inheritance pattern and variable expressivity of fragile X-associated disorders, cause significant stress for newly identified expectant couples and pose unique challenges for genetic counselors in the prenatal setting. © 2016 John Wiley & Sons, Ltd.

Molecular Correlates and Recent Advancements in the Diagnosis and Screening of FMR1-Related Disorders

Fragile X syndrome (FXS) is the most common monogenic cause of intellectual disability and autism. Molecular diagnostic testing of FXS and related disorders (fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS)) relies on a combination of polymerase chain reaction (PCR) and Southern blot (SB) for the fragile X mental retardation 1 (FMR1) CGG-repeat expansion and methylation analyses. Recent advancements in PCR-based technologies have enabled the characterization of the complete spectrum of CGG-repeat mutation, with or without methylation assessment, and, as a result, have reduced our reliance on the labor- and time-intensive SB, which is the gold standard FXS diagnostic test. The newer and more robust triplet-primed PCR or TP-PCR assays allow the mapping of AGG interruptions and enable the predictive analysis of the risks of unstable CGG expansion during mother-to-child transmission. In this review, we have summarized the correlation between several molecular elements, including CGG-repeat size, methylation, mosaicism and skewed X-chromosome inactivation, and the extent of clinical involvement in patients with FMR1-related disorders, and reviewed key developments in PCR-based methodologies for the molecular diagnosis of FXS, FXTAS and FXPOI, and large-scale (CGG)_n expansion screening in newborns, women of reproductive age and high-risk populations.

Importance of a specialty clinic for individuals with fragile X syndrome

Advances in human genetics have identified a significant number of genetic disorders associated with intellectual disability. As a result, appropriate clinical management of these affected individuals and their family members have become critical in addressing medical needs to improve quality of life. We examine the importance of a Fragile X Clinic for individuals with fragile X syndrome (FXS) and their family members by conducting a retrospective chart review of 123 new patients with FXS evaluated at the Fragile X Clinic at Emory University. After the initial diagnosis of a proband with FXS with cascade testing, there were 345 family members identified with a mutation (70% with premutations; 30% with full mutations). In terms of the impact of the clinic visit, males had a substantial number of new diagnoses in all behavioral disorders (P < 0.001), with anxiety (62%) being the most common. For female probands, the most frequent diagnosis was also anxiety (87%). Prior to the clinic visit, very few patients were prescribed psychotropic medications. After the clinic visit, the most frequently prescribed psychotropic medications for males were stimulants (41%; P < 0.001) and SSRIs (40%; P < 0.001). For females, only stimulants (33%; P = 0.03) and SSRIs (44%; P = 0.008) were statistically significantly prescribed. Our results revealed that there is a gap in care to address the co-morbid behavioral issues, psychopharmacologic medication management, and genetic counseling needs regarding FXS. A multidisciplinary setting and approach, such as that offered by a Fragile X Clinic, is one method of treating the complex needs of patients with FXS. © 2016 Wiley Periodicals, Inc.

Neuropsychiatry of fragile X-premutation carriers with and without fragile X-associated tremor-ataxia syndrome: implications for neuropsychology

OBJECTIVES

Clinical neuropsychologists benefit from clinical currency in recently ascertained neuropsychiatric illness, such as fragile X premutation (FXPM) disorders. The author reviewed the clinical literature through 2016 for neuropsychiatric phenotypes in FXPM disorders, including patients with fragile X-associated tremor/ataxia syndrome (FXTAS).

METHODS

A PubMed search using the search terms 'Fragile X,' 'Premutation,' 'Carriers,' 'Psychiatric,' 'Dementia,' 'Mood,' and 'Anxiety' for citations in the clinical literature through 2016 was reviewed for studies specifically examining the neuropsychiatric phenotype in FXPM patients. The relevant articles were classified according to specific neuropsychiatric syndromes, including child onset, adult onset with and without FXTAS, as well as common systemic comorbidities in FXPM patients.

RESULTS

Eighty-six articles were reviewed for the neuropsychiatric and other phenotypes in FXPM patients. The neuropsychiatric phenotype in FXPM patients is distinct from that of full mutation (Fragile X Syndrome) patients. FXTAS is associated with a specific cortical-subcortical major or mild neurocognitive disorder (NCD).

CONCLUSIONS

FXPM patients are at risk for neuropsychiatric illness. In addition, FXPM patients are at risk for other systemic conditions that should raise suspicion for FXPM-associated illnesses. Clinicians should consider a diagnosis of FXPM-associated neuropsychiatric illness when patients with specific clinical scenarios are encountered; especially in patient pedigrees consistent with a typical (often multigenerational) presentation of fragile X-associated conditions, confirmatory genetic testing should be considered. Clinical management should take into account the psychological challenges of a multigenerational genetic neuropsychiatric illness with a variable CNS and systemic clinical phenotype.

Genetic Counseling for Autism Spectrum Disorder in an Evolving Theoretical Landscape

PURPOSE OF REVIEW

Psychiatry is steadily moving toward a new conceptualization of brain disorders that blurs long-held diagnostic distinctions among neurodevelopmental and psychiatric conditions, including autism. Genomic discoveries are driving these changing perceptions, yet there has so far been minimal impact on traditional genetic counseling practices that continue to view autism through the lens of a dichotomous, all-or-none risk model.

RECENT FINDINGS

High rates of comorbidity exist across autism spectrum disorder, schizophrenia, intellectual disability, and other brain-based disorders. Recent epidemiological studies have shown that co-occurrence of neurodevelopmental and psychiatric disorders is the rule, rather than the exception, in affected individuals and within families. Moreover, studies of chromosomal microarray analysis and whole exome sequencing have now detected many of the same pathogenic copy number and sequence-level variants across cohorts with different clinical presentations.

SUMMARY

Going forward, the genetic counseling field will need to significantly adapt its approaches to pedigree interpretation, variant analysis, and patient education to more precisely describe both the chance and the nature of autism recurrence in terms of a continuum of brain dysfunction. These efforts will have implications for multiple practice areas and require philosophical changes for experienced practitioners and for the training of new genetic counselors. Resetting entrenched dichotomous notions about autism and other brain-based manifestations of genetic conditions will require a strategic educational effort on the part of the genetic counseling profession.

[Triplet expansion cytosine-guanine-guanine: Three cases of OMIM syndrome in the same family]

INTRODUCTION

The dynamic increase in the number of triplet repeats of cytosine-guanine-guanine (CGG) in the FMR1 gene mutation is responsible for three OMIM syndromes with a distinct clinical phenotype: Fragile X syndrome (FXS) and two pathologies in adult carriers of the premutation (55-200 CGG repeats): Primary ovarian insufficiency (FXPOI) and tremor-ataxia syndrome (FXTAS) associated with FXS.

CLINICAL OBSERVATION AND METHODS

CGG mutation dynamics of the FMR1 gene were studied in DNA samples from peripheral blood from the index case and other relatives of first, second and third degree by TP-PCR, and the percentage methylation.

RESULTS

Diagnosis of FXS was confirmed in three patients (21.4%), eight patients (57.1%) were confirmed in the premutation range transmitters, one male patient with full mutation/permutation mosaicism (7.1%) and two patients (14.3%) with normal study. Of the eight permutated patients, three had FXPOI and one male patient had FXTAS.

DISCUSSION

Our study suggests the importance of making an early diagnosis of SXF in order to carry out a family study and genetic counselling, which allow the identification of new cases or premutated patients with FMR1 gene- associated syndromes (FXTAS, FXPOI).

"It gives them more options": preferences for preconception genetic carrier screening for fragile X syndrome in primary healthcare

This study aims to explore stakeholder views about offering population-based genetic carrier screening for fragile X syndrome. A qualitative study using interviews and focus groups with stakeholders was undertaken to allow for an in-depth exploration of views and perceptions about practicalities of, and strategies for, offering carrier screening for fragile X syndrome to the general population in healthcare settings. A total of 188 stakeholders took part including healthcare providers (n = 81), relatives of people with fragile X syndrome (n = 29), and members of the general community (n = 78). The importance of raising community awareness about screening and providing appropriate support for carriers was emphasized. There was a preference for preconception carrier screening and for providing people with the opportunity to make an informed decision about screening. Primary care was highlighted as a setting which would ensure screening is accessible; however, challenges of offering screening in primary care were identified including time to discuss screening, knowledge about the test and possible outcomes, and the health professionals' approach to offering screening. With the increasing availability of genetic carrier tests, it is essential that research now focuses on evaluating approaches for the delivery of carrier screening programs. Primary healthcare is perceived as an appropriate setting through which to access the target population, and raising awareness is essential to making genetic screening more accessible to the general community.

Molecular medicine of fragile X syndrome: based on known molecular mechanisms

BACKGROUND

Extensive research on fragile X mental retardation gene knockout mice and mutant Drosophila models has largely expanded our knowledge on mechanism-based treatment of fragile X syndrome (FXS). In light of these findings, several clinical trials are now underway for therapeutic translation to humans.

DATA SOURCES

Electronic literature searches were conducted using the PubMed database and ClinicalTrials.gov. The search terms included "fragile X syndrome", "FXS and medication", "FXS and therapeutics" and "FXS and treatment". Based on the publications identified in this search, we reviewed the neuroanatomical abnormalities in FXS patients and the potential pathogenic mechanisms to monitor the progress of FXS research, from basic studies to clinical trials.

RESULTS

The pathological mechanisms of FXS were categorized on the basis of neuroanatomy, synaptic structure, synaptic transmission and fragile X mental retardation protein (FMRP) loss of function. The neuroanatomical abnormalities in FXS were described to motivate extensive research into the region-specific pathologies in the brain responsible for FXS behavioural manifestations. Mechanism-directed molecular medicines were classified according to their target pathological mechanisms, and the most recent progress in clinical trials was discussed.

CONCLUSIONS

Current mechanism-based studies and clinical trials have greatly contributed to the development of FXS pharmacological therapeutics. Research examining the extent to which these treatments provided a rescue effect or FMRP compensation for the developmental impairments in FXS patients may help to improve the efficacy of treatments.

Pre- and post-test genetic counseling for chromosomal and Mendelian disorders

Genetic carrier screening, prenatal screening for aneuploidy, and prenatal diagnostic testing have expanded dramatically over the past 2 decades. Driven in part by powerful market forces, new complex testing modalities have become available after limited clinical research. The responsibility for offering these tests lies primarily on the obstetrical care provider and has become more burdensome as the number of testing options expands. Genetic testing in pregnancy is optional, and decisions about undergoing tests, as well as follow-up testing, should be informed and based on individual patients' values and needs. Careful pre- and post-test counseling is central to supporting informed decision-making. This article explores three areas of technical expansion in genetic testing: expanded carrier screening, non-invasive prenatal screening for fetal aneuploidies using cell-free DNA, and diagnostic testing using fetal chromosomal microarray testing, and provides insights aimed at enabling the obstetrical practitioner to better support patients considering these tests.

Ethical and policy issues in newborn screening of children for neurologic and developmental disorders

Genetic testing for neurologic and developmental disorders spans the spectrum from universal newborn screening for conditions like phenylketonuria to diagnostic testing for suspected genetic conditions, to predictive genetic testing for childhood-onset conditions. Given that virtually all children in the United States undergo genetic screening in the newborn period, this article focuses on 3 actual case studies of neurologic and developmental disorders that have been included or proposed for inclusion in newborn screening programs: Duchenne muscular dystrophy (a neuromuscular disorder), Krabbe disease (a neurodegenerative disorder), and fragile X syndrome (a neurodevelopmental disorder).

Expanded carrier screening in reproductive medicine-points to consider: a joint statement of the American College of Medical Genetics and Genomics, American College of Obstetricians and Gynecologists, National Society of Genetic Counselors, Perinatal Quality Foundation, and Society for Maternal-Fetal Medicine

The Perinatal Quality Foundation and the American College of Medical Genetics and Genomics, in association with the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the National Society of Genetic Counselors, have collaborated to provide education for clinicians and laboratories regarding the use of expanded genetic carrier screening in reproductive medicine. This statement does not replace current screening guidelines, which are published by individual organizations to direct the practice of their constituents. As organizations develop practice guidelines for expanded carrier screening, further direction is likely. The current statement demonstrates an approach for health care providers and laboratories who wish to or who are currently offering expanded carrier screening to their patients.

Carrier Screening: Past, Present, and Future

To date, preconceptual and prenatal patients have been offered gene-by-gene, disorder-by-disorder carrier screening. Newer techniques allow screening of many disorders at one time. The goal of this review is to provide an overview of the current practice and future direction of carrier screening within the preconceptual/prenatal setting.

The role of AGG interruptions in fragile X repeat expansions: a twenty-year perspective

In 1994, it was suggested that AGG interruptions affect the stability of the fragile X triplet repeat. Until recently, however, this hypothesis was not explored on a large scale due primarily to the technical difficulty of determining AGG interruption patterns of the two alleles in females. The recent development of a PCR technology that overcomes this difficulty and accurately identifies the number and position of AGGs has led to several studies that examine their influence on repeat stability. Here, we present a historical perspective of relevant studies published during the last 20 years on AGG interruptions and examine those recent publications that have refined risk estimates for repeat instability and full-mutation expansions.

The FMR1 gene, infertility, and reproductive decision-making: a review

The strongest association between FMR1 and the ovary in humans is the increased risk of premature ovarian failure (POF) in women who carry the premutation level of CGG repeats (55–199 CGGs). Research on the FMR1 gene has extended to other endpoints of relevance in the OB/GYN setting for women, including infertility and ovarian hormones. After reviewing the nomenclature changes that have occurred in recent years, this article reviews the evidence linking the length of the FMR1 repeat length to fertility and ovarian hormones (follicle stimulating hormone and anti-mullerian hormone as the primary methods to assess ovarian reserve in clinical settings). The literature is inconsistent on the association between the FMR1 trinucleotide repeat length and infertility. Elevated levels of follicle stimulating hormone have been found in women who carry the premutation; however the literature on the relationship between anti-mullerian hormone and the CGG repeat length are too disparate in design to make a summary statement. This article considers the implications of two transgenic mouse models (FXPM 130R and YAC90R) for theories on pathogenesis related to ovarian endpoints. Given the current screening/testing recommendations for reproductive age females and the variability of screening protocols in clinics, future research is recommended on pretest and posttest genetic counseling needs. Future research is also needed on ovarian health measurements across a range of CGG repeat lengths in order to interpret FMR1 test results in reproductive age women; the inconsistencies in the literature make it quite challenging to advise women on their risks related to FMR1 repeat length.

In the Gray Zone in the Fragile X Gene: What are the Key Unanswered Clinical and Biological Questions?

Smaller expansions (41–54 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene are termed “gray zone” alleles. Only recently has interest in these expansions increased due to reporting of phenotypes unique to gray zone carriers or similar to those seen in individuals with larger expansions. As minimal research has focused on gray zone expansions, this paper asks several questions related to this topic. These include the following: What is the definition of the gray zone? Is there a risk of developing neurological signs in these carriers? Are there secondary gene effects that impact gray zone alleles or a biologic advantage to carrying these repeats? How do we counsel patients with gray zone expansions? The answers to these questions will help to determine the significance of these expansions and provide needed information to the research community and clinicians.

Climbing the branches of a family tree: diagnosis of fragile X syndrome

OBJECTIVE

To determine the average number of family members diagnosed with a Fragile X Mental Retardation-1 (FMR1) mutation after a proband receives the initial diagnosis of fragile X syndrome (FXS).

STUDY DESIGN

We reviewed pedigrees of families who had been evaluated at the Fragile X Syndrome Center at Emory University in Atlanta, Georgia. Through these pedigrees, we determined the number of additional family members diagnosed as FMR1 premutation carriers or with full mutation FXS after the initial diagnosis in each proband.

RESULTS

The fragile X pedigree review identified 176 probands, including 108 males (61%) and 68 females (39%). A total of 785 family members were diagnosed with expanded fragile X alleles, including 278 males (35%) and 507 females (65%). These family members included 227 individuals with full mutation FXS (219 males and 8 females) and 558 premutation carriers (59 males and 499 females). After the initial diagnosis of a proband with FXS, on average at least 5 additional family members were diagnosed with an FMR1 mutation.

CONCLUSION

Our findings confirm that obtaining a detailed family history after diagnosis of a proband with FXS is likely to identify multiple family members with FMR1 mutations. It is important that the pediatrician or other health care provider making a diagnosis of FXS recognize the value of a detailed family history for timely diagnosis and treatment of additional individuals who may be FMR1 premutation carriers or have full mutation FXS.

Attitudes towards potentially carrying the FMR1 premutation: before vs after testing of non-carrier females with diminished ovarian reserve

Diminished ovarian reserve (DOR) and premature ovarian failure are associated with elevated FMR1 CGG repeat alleles. We assessed pretest attitudes about potentially carrying the FMR1 premutation (FXP) (>55 CGG repeats) among reproductive age women compared with attitudes after learning their non-carrier status. Ninety-two women with DOR, regular menses and no family history of Fragile X Syndrome underwent FMR1 testing and completed attitudinal questionnaires before (T1) and 3 months after learning the test results (T2). The analysis utilized signed rank tests and α = 0.05. Very few women thought they were likely to have a FXP (6.6%). More participants thought FMR1 premutations were "serious" at T2 (62.9%) than at T1 (46.1%, p < 0.0003). When asked at T1 to "describe your feelings when you consider that you are potentially a carrier" of a FXP, 10% had negative feelings, 50% felt ambivalent, and 40% had positive feelings. At T2, feelings about not being a carrier were significantly more favorable (p < 0.0001): negative (0%), ambivalent (6.5%), positive (93%). Corroborating prior reports, few women had a negative view of FXP, perhaps anticipating that carrying the FXP explains their infertility. Perception of the seriousness of FXP increased after learning they did not carry the FXP, which would be predicted by health belief models.

Offering fragile X syndrome carrier screening: a prospective mixed-methods observational study comparing carrier screening of pregnant and non-pregnant women in the general population

INTRODUCTION

Fragile X syndrome (FXS) is the leading cause of inherited intellectual and developmental disability. Policy development relating to carrier screening programmes for FXS requires input from large studies examining not only test uptake but also psychosocial aspects. This study will compare carrier screening in pregnant and non-pregnant populations, examining informed decision-making, psychosocial issues and health economics.

METHODS AND ANALYSIS

Pregnant and non-pregnant women are being recruited from general practices and obstetric services. Women receive study information either in person or through clinic mail outs. Women are provided pretest counselling by a genetic counsellor and make a decision about testing in their own time. Data are being collected from two questionnaires: one completed at the time of making the decision about testing and the second 1 month later. Additional data are gathered through qualitative interviews conducted at several time points with a subset of participating women, including all women with a positive test result, and with staff from recruiting clinics. A minimum sample size of 500 women/group has been calculated to give us 88% power to detect a 10% difference in test uptake and 87% power to detect a 10% difference in informed choice between the pregnant and non-pregnant groups. Questionnaire data will be analysed using descriptive statistics and multivariate logistic regression models. Interview data will be thematically analysed. Willingness-to-pay and cost effectiveness analyses will also be performed. Recruitment started in July 2009 and data collection will be completed by December 2013.

ETHICS AND DISSEMINATION

Ethics approval has been granted by the Universities of Melbourne and Western Australia and by recruiting clinics, where required. Results will be reported in peer-reviewed publications, conference presentations and through a website http://www.fragilexscreening.net.au. The results of this study will make a significant contribution to discussions about the wider introduction of population carrier screening for FXS.

Attitude of medical school students in China towards genetic testing and counseling issues in FXS

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability. However, genetic testing protocols and genetic counseling guidelines for FXS are not yet established in mainland China. In the present study, we conducted a comprehensive analysis using a self-administered questionnaire among students at the Xiangya medical school to investigate their attitude towards genetic testing and counseling issues of FXS. We have gained a general understanding of the attitudes of medical students towards these FXS issues in China. This information is of immense importance to develop appropriate genetic tests and to train counselors for FXS. As the medical school students surveyed are prospective physicians who will be a part of the Chinese health system, our survey was focused on the basic knowledge of FXS, population-based FXS screening, confidentiality and reproductive options for mutation carriers. The study demonstrated that only less than one third of the participants had heard about FXS. 94.6 % of participants were in favor of FXS screening for women in their reproductive age who had a genetic history of FXS. Furthermore, only half of the participants would inform their families about their genetic status in case of positive test results, and more than half of the participants supported natural conception and prenatal diagnosis for FXS mutation carriers. Additional findings and research implications are also discussed. This survey targeting potential doctors provides important information for the development of FXS genetic test and counselor training for the Chinese health system.

Knowledge and perceptions about fragile X syndrome: implications for diagnosis, intervention, and research

We surveyed 439 professionals in the field of autism to assess their knowledge and perceptions about fragile X syndrome (FXS) and related issues. Almost half had worked with at least one child diagnosed with FXS, yet most lacked basic knowledge about the condition, underestimated its significance in the etiology of autism spectrum disorders, and rarely accessed fragile X-specific resources. A majority perceived etiology to be an important variable in therapeutic response while three quarters felt that professionals in the field of autism should play an active role in referring children for etiological evaluation. Despite these opinions, most respondents either rarely or never inquired about etiology when working with a new client. The survey results underscore the need for training and education so that autism professionals can become effective partners in diagnostic genetic referral and in research and implementation of syndrome-specific interventions.

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.

The relationship between the number of CGG repeats and serum level of anti-Müllerian hormone in women without FMR1 premutation

OBJECTIVE

To investigate the relationship between the number of CGG repeats in the fragile X mental retardation 1 (FMR1) gene and serum levels of anti-Müllerian hormone (AMH) in Korean infertility patients without premutation.

STUDY DESIGN

A retrospective study of 228 infertile women who received fertility treatment in a single private in vitro fertilization (IVF) clinic from May 2010 to August 2012 was performed. Serum FSH and AMH were measured on menstrual day 3 and the number of CGG repeats was evaluated.

RESULTS

The mean age of the study population was 33.3±3.8 years. No significant correlation was observed between CGG repeat count in both alleles and the serum FSH, AMH or multiples of median (MoM) of AMH in whole study subjects. In women with age ≥35 years, however, there was an increasing tendency in the MoM of AMH with increasing number of CGG repeats in allele 2 (R(2)=0.075, p=0.008). This correlation was not observed in patients aged less than 35 years.

CONCLUSION

We observed a positive correlation between MoM of AMH and number of CGG repeats in allele 2 in women aged over 35 years. Our findings are discordant with other reports, and therefore further studies are needed to determine whether this discrepancy is due to ethnic differences.