Case ReportHypothyroidism could be the only manifestation of mitochondrial T8993C mutation in Leigh syndrome

Mitochondrial DNA-associated Leigh syndrome is a part of a continuum of progressive neurodegenerative disorders caused by abnormalities of mitochondrial energy generation. Mitochondrial T8993C and T8993G mutations account for 10–20% of these cases. T8993C is generally associated with milder phenotype than T8993G mutation. Here we report an Egyptian family with T8993C mutation with unusual early onset of severe phenotype in three sisters (consisting of regression of previously acquired motor and mental milestones after an attack of viral infection) and hypothyroidism as the only presenting symptom in their brother. The mother (like her son) carried the T8993C mutation and was asymptomatic. This unusual lack of manifestation could be attributed to different percentages of mutated mitochondrial DNA in the brain or muscle or perhaps to some unknown protective factor. The hypothyroidism could be a simple association, but to the best of our knowledge, no previous reports have described hypothyroidism in carriers of this mutation.Keywords: Leigh syndrome; Mitochondria; HypothyroidismThe Egyptian Journal of Medical Human Genetics (2013) 14, 201–20

Case ReportHypothyroidism could be the only manifestation of mitochondrial T8993C mutation in Leigh syndrome

Mitochondrial DNA-associated Leigh syndrome is a part of a continuum of progressive neurodegenerative disorders caused by abnormalities of mitochondrial energy generation. Mitochondrial T8993C and T8993G mutations account for 10–20% of these cases. T8993C is generally associated with milder phenotype than T8993G mutation. Here we report an Egyptian family with T8993C mutation with unusual early onset of severe phenotype in three sisters (consisting of regression of previously acquired motor and mental milestones after an attack of viral infection) and hypothyroidism as the only presenting symptom in their brother. The mother (like her son) carried the T8993C mutation and was asymptomatic. This unusual lack of manifestation could be attributed to different percentages of mutated mitochondrial DNA in the brain or muscle or perhaps to some unknown protective factor. The hypothyroidism could be a simple association, but to the best of our knowledge, no previous reports have described hypothyroidism in carriers of this mutation.Keywords: Leigh syndrome; Mitochondria; HypothyroidismThe Egyptian Journal of Medical Human Genetics (2013) 14, 201–20

Effects of mavoglurant on visual attention and pupil reactivity while viewing photographs of faces in Fragile X Syndrome.

BackgroundNumerous preclinical studies have supported the theory that enhanced activation of mGluR5 signaling, due to the absence or reduction of the FMR1 protein, contributes to cognitive and behavioral deficits in patients with fragile X syndrome (FXS). However multiple phase 2 controlled trials in patients with FXS have failed to demonstrate efficacy of compounds that negatively modulate mGluR5, including two phase 2b randomized controlled trials (RCT) of mavoglurant (AFQ056, Novartis Pharma AG), when the primary measures of interest were behavioral ratings. This has cast some doubt onto the translation of the mGluR5 theory from animal models to humans with the disorder.MethodsWe evaluated social gaze behavior-a key phenotypic feature of the disorder-and sympathetic nervous system influence on pupil size using a previously-validated eye tracking paradigm as a biobehavioral probe, in 57 adolescent or adult patients with FXS at baseline and following three months of blinded treatment with one of three doses of mavoglurant or placebo, within the context of the AFQ056 RCTs.ResultsPatients with FXS treated with mavoglurant demonstrated increased total absolute looking time and number of fixations to the eye region while viewing human faces relative to baseline, and compared to those treated with placebo. In addition, patients had greater pupil reactivity to faces relative to baseline following mavoglurant treatment compared to placebo.DiscussionThe study shows that negative modulation of mGluR5 activity improves eye gaze behavior and alters sympathetically-driven reactivity to faces in patients with FXS, providing preliminary evidence of this drug's impact on behavior in humans with the disorder

Emerging therapeutic strategies for Fragile X Syndrome:Q&A

Understanding how best to treat aspects of Fragile X syndrome has the potential to improve the quality of life of affected individuals. Such an effective therapy has, as yet, remained elusive. In this article, we ask those researching or affected by Fragile X syndrome their views on the current state of research and from where they feel the most likely therapy may emerge

Improving IQ measurement in intellectual disabilities using true deviation from population norms

BackgroundIntellectual disability (ID) is characterized by global cognitive deficits, yet the very IQ tests used to assess ID have limited range and precision in this population, especially for more impaired individuals.MethodsWe describe the development and validation of a method of raw z-score transformation (based on general population norms) that ameliorates floor effects and improves the precision of IQ measurement in ID using the Stanford Binet 5 (SB5) in fragile X syndrome (FXS; n = 106), the leading inherited cause of ID, and in individuals with idiopathic autism spectrum disorder (ASD; n = 205). We compared the distributional characteristics and Q-Q plots from the standardized scores with the deviation z-scores. Additionally, we examined the relationship between both scoring methods and multiple criterion measures.ResultsWe found evidence that substantial and meaningful variation in cognitive ability on standardized IQ tests among individuals with ID is lost when converting raw scores to standardized scaled, index and IQ scores. Use of the deviation z- score method rectifies this problem, and accounts for significant additional variance in criterion validation measures, above and beyond the usual IQ scores. Additionally, individual and group-level cognitive strengths and weaknesses are recovered using deviation scores.ConclusionTraditional methods for generating IQ scores in lower functioning individuals with ID are inaccurate and inadequate, leading to erroneously flat profiles. However assessment of cognitive abilities is substantially improved by measuring true deviation in performance from standardization sample norms. This work has important implications for standardized test development, clinical assessment, and research for which IQ is an important measure of interest in individuals with neurodevelopmental disorders and other forms of cognitive impairment

Developmental profiles of infants with an FMR1 premutation

Abstract Background Emerging evidence suggests that a subset of FMR1 premutation carriers is at an increased risk for cognitive, emotional, and medical conditions. However, because the premutation is rarely diagnosed at birth, the early developmental trajectories of children with a premutation are not known. Methods This exploratory study examined the cognitive, communication, and social-behavioral profiles of 26 infants with a premutation who were identified through participation in a newborn screening for fragile X syndrome pilot study. In this study, families whose newborn screened positive for an FMR1 premutation were invited to participate in a longitudinal study of early development. Twenty-six infants with the premutation and 21 matched, screen-negative comparison babies were assessed using validated standardized measures at 6-month intervals starting as young as 3 months of age. The babies were assessed up to seven times over a 4-year period. Results The premutation group was not statistically different from the comparison group on measures of cognitive development, adaptive behavior, temperament, or overall communication. However, the babies with the premutation had a significantly different developmental trajectory on measures of nonverbal communication and hyperresponsivity to sensory experiences. They also were significantly more hyporesponsive at all ages than the comparison group. Cytosine-guanine-guanine repeat length was linearly associated with overall cognitive development. Conclusions These results suggest that infants with a premutation may present with subtle developmental differences as young as 12 months of age that may be early markers of later anxiety, social deficits, or other challenges thought to be experienced by a subset of carriers

Inhibition Deficits Are Modulated by Age and CGG Repeat Length in Carriers of the \u3ci\u3eFMR1\u3c/i\u3e Premutation Allele Who Are Mothers of Children With Fragile X Syndrome

Individuals who carry a premutation (PM) allele on the FMR1 gene may experience executive limitations associated with their genetic status, including inhibition deficits. However, poor understanding of individualized risk factors has limited clinical management of this group, particularly in mothers who carry the PM allele who have children with fragile X syndrome (FXS). The present study examined CGG repeat length and age as factors that may account for variable expressivity of inhibition deficits. Participants were 134 carriers of the PM allele who were mothers of children with FXS. Inhibition skills were measured using both self-report and direct behavioral assessments. Increased vulnerability for inhibition deficits was observed at mid-range CGG lengths of approximately 80-100 repeats, with some evidence of a second zone of vulnerability occurring at approximately 130-140 CGG repeats. Risk associated with the genotype also became more pronounced with older age. This study identifies personalized risk factors that may be used to tailor the clinical management of executive deficits in carriers of the PM allele. Inhibition deficits may contribute to poor outcomes in carriers of the PM allele and their families, particularly in midlife and early old age, and clinical monitoring may be warranted

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