Maternal attitudes to newborn screening for fragile X syndrome

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.

Parental Experiences of Genetic Testing

Genetic testing is increasingly used in clinical practice in the neonatal period, including in NICUs. This testing may have psychological consequences for parents. To best support families, neonatal clinicians should be aware of the various ways in which parents view and respond to genetic testing. In this review, we summarize research on the parental experience of having a newborn infant undergo genetic testing.

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.

Research Gaps in Fragile X Syndrome: An Updated Literature Review to Inform Clinical and Public Health Practice

OBJECTIVE

The phenotypic impact of fragile X syndrome (FXS) has been well-documented since the discovery of the fragile X messenger ribonucleoprotein 1 gene 30 years ago. However, gaps remain in clinical and public health research. The purpose of this literature review was to determine the extent to which these gaps have been addressed and identify targeted areas of future research.

METHODS

We conducted an electronic search of several scientific databases using a variety of key words. The search focused on 5 areas identified as research gaps by an earlier review: (1) diagnosis, (2) phenotypic presentation, (3) familial impact, (4) interventions and treatments, and (5) life span perspectives. Inclusion criteria included publication between 2014 and 2020, focus on human subjects, and publication in English. A total of 480 articles were identified, 365 were reviewed, and 112 are summarized in this review.

RESULTS

Results are organized into the following categories: (1) FXS phenotype and subtypes (FXS subtypes, medical profile, cognitive/developmental profile, social and behavioral profile); (2) needs of adults; (3) public health needs (clinical diagnosis and newborn screening, health care needs, and access); (4) treatment (treatment priorities, pharmacological treatments, and behavioral and educational interventions); and (5) families (economic burden and mother-child relationship).

CONCLUSION

Despite the progress in many areas of FXS research, work remains to address gaps in clinical and public health knowledge. We pose 3 main areas of focused research, including early detection and diagnosis, determinants of health, and development and implementation of targeted interventions.

Psychosocial Issues Related to Newborn Screening: A Systematic Review and Synthesis

Genomic advances have contributed to a proliferation of newborn screening (NBS) programs. Psychosocial consequences of NBS have been identified as risks to these public health initiatives. Following PRISMA guidelines, this systematic review synthesizes findings from 92 evidence-based, peer-reviewed research reports published from 2000 through 2020 regarding psychosocial issues associated with NBS. Results describe parents' knowledge of and attitudes towards NBS, reactions to and understanding of positive NBS results, experiences of communication with health providers, decisions about carrier testing, and future pregnancies. Findings also explain the impact of positive NBS results on parent-child relationships, child development, informing children about carrier status, family burden, quality of life, and disparities. In conclusion, psychosocial consequences of receiving unexpected neonatal screening results and unsolicited genetic information remain significant risks to expansion of NBS. Findings suggest that risks may be mitigated by improved parent NBS education, effective communication, individualized genetic counseling, and anticipatory developmental guidance. Clinicians need to take extra measures to ensure equitable service delivery to marginalized subpopulations. Future investigations should be more inclusive of culturally and socioeconomically diverse families and conducted in low-resource countries. Providing these countries with adequate resources to develop NBS programs is an essential step towards achieving international health equity.

Acceptability of childhood screening: a systematic narrative review

Objectives

A systematic narrative literature review was undertaken to assess the acceptability of childhood screening interventions to identify factors to consider when planning or modifying childhood screening programs to maximize participation and uptake.

Study design

This is a systematic narrative literature review.

Methods

Electronic databases were searched (MEDLINE, EMBASE, PsycINFO via Ovid, CINAHL, and Cochrane Library) to identify primary research studies that assessed screening acceptability. Studies were categorized using an existing theoretical framework of acceptability consisting of seven constructs: affective attitude, burden, ethicality, intervention coherence, opportunity costs, perceived effectiveness, and self-efficacy. A protocol was developed and registered with PROSPERO (registration no. CRD42018099763)

Results

The search identified 4529 studies, and 46 studies met the inclusion criteria. Most studies involved neonatal screening. Programs identified included newborn blood spot screening (n = 22), neonatal hearing screening (n = 13), Duchenne muscular dystrophy screening (n = 4), cystic fibrosis screening (n = 3), screening for congenital heart defects (n = 2), and others (n = 2). Most studies assessed more than one construct of acceptability. The most common constructs identified were affective attitude (how a parent feels about the program) and intervention coherence (parental understanding of the program, and/or the potential consequences of a confirmed diagnosis).

Conclusions

The main acceptability component identified related to parental knowledge and understanding of the screening process, the testing procedure(s), and consent. The emotional impact of childhood screening mostly explored maternal anxiety. Further studies are needed to examine the acceptability of childhood screening across the wider family unit. When planning new (or refining existing) childhood screening programs, it is important to assess acceptability before implementation. This should include assessment of important issues such as information needs, timing of information, and when and where the screening should occur.

DNA Methylation at Birth Predicts Intellectual Functioning and Autism Features in Children with Fragile X Syndrome

Fragile X syndrome (FXS) is a leading single-gene cause of intellectual disability (ID) with autism features. This study analysed diagnostic and prognostic utility of the Fragile X-Related Epigenetic Element 2 DNA methylation (FREE2m) assessed by Methylation Specific-Quantitative Melt Analysis and the EpiTYPER system, in retrospectively retrieved newborn blood spots (NBS) and newly created dried blood spots (DBS) from 65 children with FXS (~2–17 years). A further 168 NBS from infants from the general population were used to establish control reference ranges, in both sexes. FREE2m analysis showed sensitivity and specificity approaching 100%. In FXS males, NBS FREE2m strongly correlated with intellectual functioning and autism features, however associations were not as strong for FXS females. Fragile X mental retardation 1 gene (FMR1) mRNA levels in blood were correlated with FREE2m in both NBS and DBS, for both sexes. In females, DNAm was significantly increased at birth with a decrease in childhood. The findings support the use of FREE2m analysis in newborns for screening, diagnostic and prognostic testing in FXS.

Are We Ready for Fragile X Newborn Screening Testing?-Lessons Learnt from a Feasibility Study

Fragile X syndrome (FXS) is the most prevalent heritable cause of cognitive impairment but is not yet included in a newborn screening (NBS) program within Australia. This paper aims to assess the feasibility and reliability of population screening for FXS using a pilot study in one hospital. A total of 1971 mothers consented for 2000 newborns to be tested using routine NBS dried blood spot samples. DNA was extracted and a modified PCR assay with a chimeric CGG primer was used to detect fragile X alleles in both males and females in the normal, premutation, and full mutation ranges. A routine PCR-based fragile X assay was run in parallel to validate the chimeric primer assay. Babies with CGG repeat number ≥59 were referred for family studies. One thousand nine hundred and ninety NBS samples had a CGG repeat number less than 55 (1986 < 50); 10 had premutation alleles >54 CGG repeats (1/123 females and 1/507 males). There was complete concordance between the two PCR-based assays. A recent review revealed no clinically identified cases in the cohort up to 5 years later. The cost per test was $AUD19. Fragile X status can be determined on routine NBS samples using the chimeric primer assay. However, whilst this assay may not be considered cost-effective for population screening, it could be considered as a second-tier assay to a developed immunoassay for fragile X mental retardation protein (FMRP).

Fragile X Newborn Screening: Lessons Learned From a Multisite Screening Study

BACKGROUND

Delays in the diagnosis of children with fragile X syndrome (FXS) suggest the possibility of newborn screening as a way to identify children earlier. However, FXS does not have a proven treatment that must be provided early, and ethical concerns have been raised about the detection of infants who are carriers. This article summarizes major findings from a multisite, prospective, longitudinal pilot screening study.

METHODS

Investigators in North Carolina, California, and Illinois collaborated on a study in which voluntary screening for FXS was offered to parents in 3 birthing hospitals. FXS newborn screening was offered to >28 000 families to assess public acceptance and determine whether identification of babies resulted in any measurable harms or adverse events. Secondary goals were to determine the prevalence of FMR1 carrier gene expansions, study the consent process, and describe early development and behavior of identified children.

RESULTS

A number of publications have resulted from the project. This article summarizes 10 "lessons learned" about the consent process, reasons for accepting and declining screening, development and evaluation of a decision aid, prevalence of carriers, father participation in consent, family follow-up, and maternal reactions to screening.

CONCLUSIONS

The project documented public acceptance of screening as well as the challenges inherent in obtaining consent in the hospital shortly after birth. Collectively, the study provides answers to a number of questions that now set the stage for a next generation of research to determine the benefits of earlier identification for children and families.

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.

Group Testing Approach for Trinucleotide Repeat Expansion Disorder Screening

BACKGROUND

Fragile X syndrome (FXS, OMIM #300624) is an X-linked condition caused by trinucleotide repeat expansions in the 5′ UTR (untranslated region) of the fragile X mental retardation 1 (FMR1) gene. FXS testing is commonly performed in expanded carrier screening and has been proposed for inclusion in newborn screening. However, because pathogenic alleles are long and have low complexity (&gt;200 CGG repeats), FXS is currently tested by a single-plex electrophoresis-resolved PCR assay rather than multiplexed approaches like next-generation sequencing or mass spectrometry. In this work, we sought an experimental design based on nonadaptive group testing that could accurately and reliably identify the size of abnormally expanded FMR1 alleles of males and females.

METHODS

We developed a new group testing scheme named StairCase (SC) that was designed to the constraints of the FXS testing problem, and compared its performance to existing group testing schemes by simulation. We experimentally evaluated SC's performance on 210 samples from the Coriell Institute biorepositories using pooled PCR followed by capillary electrophoresis on 3 replicates of each of 3 pooling layouts differing by the mapping of samples to pools.

RESULTS

The SC pooled PCR approach demonstrated perfect classification of samples by clinical category (normal, intermediate, premutation, or full mutation) for 90 positives and 1800 negatives, with a batch of 210 samples requiring only 21 assays.

CONCLUSIONS

Group testing based on SC is an implementable approach to trinucleotide repeat expansion disorder testing that offers ≥10-fold reduction in assay costs over current single-plex methods.

Biobank participant support of newborn screening for disorders with variable treatment and intervention options

We aimed to better understand biobank participant opinions of the benefits of newborn screening (NBS) for certain disorder types and how terminology used in NBS discourse might impact stakeholder opinion. We conducted a between-subjects randomized survey of 5840 members of the Northwestern University Biobank. The survey contained 12 scenarios, each describing a disorder and its treatment. For each scenario, we varied the terminology used to describe treatment options. One survey version used the term intervention and the other treatment. The outcome measured for each scenario was perceived benefit (for the infant) and importance of testing (for participants). Comparisons were made between participants and between scenarios. Ratings of benefit and importance were not influenced by the use of the term intervention versus treatment within scenarios. Nuances existed in ratings of benefit to the infant and importance to participants amongst scenarios. Participants were most likely to perceive benefit and importance in screening for a disorder if treatment/intervention offered a high chance of improved outcomes. While participants perceived benefit to the infant and importance to themselves in screening for most disorders, nuances in inter-scenario ratings suggest participants weighed availability and type of treatment/intervention in consideration of the benefits of NBS.

Parental intentions to enroll children in a voluntary expanded newborn screening program

BACKGROUND AND OBJECTIVES

Nearly all babies in the United States are tested at birth for rare, serious, and treatable disorders through mandatory state newborn screening (NBS). Recently, there have been calls for an expanded, voluntary model to facilitate early diagnosis and treatment of a wider range of disorders. We applied the reasoned action framework to examine parental intentions to participate in voluntary expanded screening.

METHODS

We recruited a national cohort of recent and expectant parents living in the U.S. who completed a self-administered online survey (N = 1001). Using a mixed-level fractional factorial experiment, we studied parental participation intentions and preferences for timing of consent, cost, consent format, and testing options.

RESULTS

We conducted a hierarchical regression analysis assessing parental intentions to participate in voluntary expanded NBS. Attitudes, perceived normative influence, and perceived behavioral control explained substantial variance in intention, with perceived normative influence emerging as the strongest predictor. We found no evidence that the manipulated program features altered mean levels of intention, but timing of parental permission, cost, and permission format moderated the relative importance of reasoned action constructs on intention.

CONCLUSION

Program design features may impact the psychological mechanisms underlying parental decision making for voluntary expanded screening. These results have important implications for parent education, outreach, and informed parental permission procedures.

Identification of a male with fragile X syndrome through newborn screening

A pilot newborn screening (NBS) study for fragile X syndrome was recently conducted at the University of California, Davis Medical Center. The screening study identified a case of a male with the full mutation completely methylated and no detectable expression of the fragile X mental retardation-1 (FMR1) gene. The patient was initially seen in clinic at the MIND Institute, for medical follow-up and a genetic counseling session at the chronological age of 3 months. Since then, he has been seen in clinic every six months for follow up, medical examination and developmental assessments. Longitudinally administered developmental testing of the infant has revealed persistent delays in development, consistent with fragile X syndrome. Cascade testing revealed that the patient's mother and two siblings also have the full mutation. The patient has been receiving speech and language therapy, combined with physical and occupational therapies on a weekly basis since the age of one year. He is currently being treated with 2.5 mg of sertraline, which has been demonstrated to be helpful for improving language in young children with the syndrome.

Assessment of the Knowledge and Attitudes of Saudi Mothers towards Newborn Screening

OBJECTIVE

To assess the attitude and knowledge of the Saudi mothers toward newborn screening (NBS) program.

METHODS

A total of 425 Saudi women (only mothers who have at least one pregnancy) participated in the study from different regions in Saudi Arabia and completed the structured questionnaire which sought their views on the NBS services.

RESULTS

A majority of the participating women (91.1%) supported the NBS program and felt it was very important and useful. However, knowledge of NBS was found to be very limited and only 34.6% knew that NBS was a test to detect genetic disorders. A lack of communication and counseling to NBS clients by health authorities offering screening is implied.

CONCLUSION

In general, there is a positive attitude towards the NBS program among Saudi women. However, they have several concerns to improve the availability of medication and formulas, genetic counseling, medical interventions, communication, education materials, and awareness.

Public Perceptions of the Benefits and Risks of Newborn Screening

BACKGROUND

Growing technological capacity and parent and professional advocacy highlight the need to understand public expectations of newborn population screening.

METHODS

We administered a bilingual (French, English) Internet survey to a demographically proportional sample of Canadians in 2013 to assess preferences for the types of diseases to be screened for in newborns by using a discrete choice experiment. Attributes were: clinical benefits of improved health, earlier time to diagnosis, reproductive risk information, false-positive (FP) results, and overdiagnosed infants. Survey data were analyzed with a mixed logit model to assess preferences and trade-offs among attributes, interaction between attributes, and preference heterogeneity.

RESULTS

On average, respondents were favorable toward screening. Clinical benefits were the most important outcome; reproductive risk information and early diagnosis were also valued, although 8% disvalued early diagnosis, and reproductive risk information was least important. All respondents preferred to avoid FP results and overdiagnosis but were willing to accept these to achieve moderate clinical benefit, accepting higher rates of harms to achieve significant benefit. Several 2-way interactions between attributes were statistically significant: respondents were willing to accept a higher FP rate for significant clinical benefit but preferred a lower rate for moderate benefit; similarly, respondents valued early diagnosis more when associated with significant rather than moderate clinical benefit.

CONCLUSIONS

Members of the public prioritized clinical benefits for affected infants and preferred to minimize harms. These findings suggest support for newborn screening policies prioritizing clinical benefits over solely informational benefits, coupled with concerted efforts to avoid or minimize harms.

Maternal Consequences of the Detection of Fragile X Carriers in Newborn Screening

OBJECTIVES

The possibility of newborn screening for fragile X syndrome is complicated by the potential for identifying premutation carriers. Although knowing the child's carrier status has potential benefits, the possibility of late-onset disorders in carrier children and their parents raises concerns about whether such information would be distressing to parents and potentially more harmful than helpful. This study sought to answer this question by offering voluntary fragile X screening to new parents and returning results for both the full mutation and premutation FMR1 gene expansions. We tested the assumption that such information could lead to adverse mental health outcomes or decision regret. We also wanted to know if child age and spousal support were associated with the outcomes of interest.

METHODS

Eighteen mothers of screen-positive infants with the premutation and 15 comparison mothers completed a battery of assessments of maternal anxiety, postpartum depression, stress, family quality of life, decision regret, and spousal support. The study was longitudinal, with an average of 3 assessments per mother.

RESULTS

The premutation group was not statistically different from the comparison group on measures of anxiety, depression, stress, or quality of life. A subset of mothers experienced clinically significant anxiety and decision regret, but factors associated with these outcomes could not be identified. Greater spousal support was generally associated with more positive outcomes.

CONCLUSIONS

Although we did not find evidence of significant adverse events, disclosure of newborn carrier status remains an important consideration in newborn screening policy.

High acceptance of an early dyslexia screening test involving genetic analyses in Germany

Dyslexia is a developmental disorder characterized by severe problems in the acquisition of reading and writing skills. It has a strong neurobiological basis. Genetic influence is estimated at 50-70%. One of the central problems with dyslexia is its late diagnosis, normally not before the end of the 2nd grade, resulting in the loss of several years for early therapy. Currently, research is focusing on the development of early tests for dyslexia, which may be based on EEG and genetics. Our aim was to determine the acceptance of such a future test among parents. We conducted a representative survey in Germany with 1000 parents of children aged 3-7 years, with and without experience of dyslexia. 88.7% of the parents supported the introduction of an early test for dyslexia based on EEG and genetics; 82.8% would have their own children tested, and 57.9% were willing to pay for the test if health insurance did not cover the costs. Test acceptance was significantly higher if parents had prior experience with dyslexia. The perceived benefits of such a test were early recognition and remediation and, preventing deficits. Concerns regarded the precision of the test, its potentially stigmatizing effect and its costs. The high overall support for the test leads to the conclusion that parents would accept a test for dyslexia based on EEG and genetics.

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).

Fragile X protein in newborn dried blood spots

Background

The fragile X syndrome (FXS) results from mutation of the FMR1 gene that prevents expression of its gene product, FMRP. We previously characterized 215 dried blood spots (DBS) representing different FMR1 genotypes and ages with a Luminex-based immunoassay (qFMRP). We found variable FMRP levels in the normal samples and identified affected males by the drastic reduction of FMRP.

Methods

Here, to establish the variability of expression of FMRP in a larger random population we quantified FMRP in 2,000 anonymous fresh newborn DBS. We also evaluated the effect of long term storage on qFMRP by retrospectively assaying 74 aged newborn DBS that had been stored for 7-84 months that included normal and full mutation individuals. These analyses were performed on 3 mm DBS disks. To identify the alleles associated with the lowest FMRP levels in the fresh DBS, we analyzed the DNA in the samples that were more than two standard deviations below the mean.

Results

Analysis of the fresh newborn DBS revealed a broad distribution of FMRP with a mean approximately 7-fold higher than that we previously reported for fresh DBS in normal adults and no samples whose FMRP level indicated FXS. DNA analysis of the lowest FMRP DBS showed that this was the low extreme of the normal range and included a female carrying a 165 CGG repeat premutation. In the retrospective study of aged newborn DBS, the FMRP mean of the normal samples was less than 30% of the mean of the fresh DBS. Despite the degraded signal from these aged DBS, qFMRP identified the FXS individuals.

Conclusions

The assay showed that newborn DBS contain high levels of FMRP that will allow identification of males and potentially females, affected by FXS. The assay is also an effective screening tool for aged DBS stored for up to four years.

Early Detection of Fragile X Syndrome: Applications of a Novel Approach for Improved Quantitative Methylation Analysis in Venous Blood and Newborn Blood Spots

BACKGROUND

Standard fragile X syndrome (FXS) diagnostic tests that target methylation of the fragile X mental retardation 1 (FMR1) CpG island 5′ of the CGG expansion can be used to predict severity of the disease in males from birth, but not in females.

METHODS

We describe methylation specific–quantitative melt analysis (MS-QMA) that targets 10 CpG sites, with 9 within FMR1 intron 1, to screen for FXS from birth in both sexes. The novel method combines the qualitative strengths of high-resolution melt and the high-throughput, quantitative real-time PCR standard curve to provide accurate quantification of DNA methylation in a single assay. Its performance was assessed in 312 control (CGG &lt;40), 143 premutation (PM) (CGG 56–170), 197 full mutation (FM) (CGG 200–2000), and 33 CGG size and methylation mosaic samples.

RESULTS

In male and female newborn blood spots, MS-QMA differentiated FM from control alleles, with sensitivity, specificity, and positive and negative predictive values between 92% and 100%. In venous blood of FM females between 6 and 35 years of age, MS-QMA correlated most strongly with verbal IQ impairment (P = 0.002). In the larger cohort of males and females, MS-QMA correlated with reference methods Southern blot and MALDI-TOF mass spectrometry (P &lt; 0.05), but was not significantly correlated with age. Unmethylated alleles in high-functioning FM and PM males determined by both reference methods were also unmethylated by MS-QMA.

CONCLUSIONS

MS-QMA has an immediate application in FXS diagnostics, with a potential use of its quantitative methylation output for prognosis in both sexes.

Newborn screening for fragile X syndrome

Fragile X syndrome (FXS), caused by a trinucleotide expansion (>200 CGG repeats) in the fragile X mental retardation gene (FMR1), is currently not included in newborn screening (NBS) panels in the United States as it does not meet the standards for recommendation. Although in the past few years FXS has met many of the criteria for population screening and studies have shown that NBS for FXS is feasible, the idea is still controversial and the debate is open. The recent advances in genomic testing as well as groundbreaking advances in targeted treatment for FXS have been challenging the dogma and principle of the national NBS program: screen only if you can intervene. Arguments in favor of NBS include benefits of early intervention and follow-up for the identified baby, which would justify NBS even in the absence of medical benefit to the child. In addition, the extended family members may benefit from genetic and reproductive counseling, informed decision making before a subsequent pregnancy, and access to treatment and services. However, communicating the results and the potential consequences to families is a challenge and could lead to a heavy psychosocial burden. A controversial issue is the identification of premutation carriers (55-200 CGG repeats), because it not only can lead to information on the reproductive possibility of having a child with FXS but also leads to information about personal health risks associated with the premutation. Yet, knowledge of carrier status could stimulate and encourage lifestyle changes and preventive measures likely to reduce the risk of medical problems reported in premutation carriers. If NBS for FXS is developed, it must be carried out with clear awareness of the potential impact on the lives of the children, and it should be done after counseling and parents' informed consent. Importantly, the infrastructure to support testing, counseling, treatment, and follow-up will have to be made available to the families.