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FXTAS IN AN UNMETHYLATED MOSAIC MALE WITH FRAGILE X SYNDROME FROM CHILE

Carriers of an FMR1 premutation allele (55–200 CGG repeats) often develop the neurodegenerative disorders, fragile X‐associated tremor/ataxia syndrome (FXTAS). Neurological signs of FXTAS, parkinsonism and rapid onset of cognitive decline have not been reported in individuals with an unmethylated full mutation (FM). Here, we report a Chilean family affected with FXS, inherited from a parent carrier of an FMR1 unmethylated full mosaic allele, who presented with a fast progressing FXTAS. This case suggests that the definition of FXTAS may need to be broadened to not only include those with a premutation but also those with an expanded allele in FM range with a lack of methylation leading to elevated FMR1‐mRNA expression levels and subsequent RNA toxicity.

Identification of Males with Cryptic Fragile X Alleles by Methylation-Specific Quantitative Melt Analysis

BACKGROUND FMR1 full mutations (FMs) (CGG expansion >200) in males mosaic for a normal (<45 CGG) or gray-zone (GZ) (45-54 CGG) allele can be missed with the standard 2-step fragile X syndrome (FXS) testing protocols, largely because the first-line PCR tests showing a normal or GZ allele are not reflexed to the second-line test that can detect FM. METHODS We used methylation-specific quantitative melt analysis (MS-QMA) to determine the prevalence of cryptic FM alleles in 2 independent cohorts of male patients (994 from Chile and 2392 from Australia) referred for FXS testing from 2006 to 2013. All MS-QMA-positive cases were retested with commercial triplet primed PCR, methylation-sensitive Southern blot, and a methylation-specific EpiTYPER-based test. RESULTS All 38 FMs detected with the standard 2-step protocol were detected with MS-QMA. However, MS-QMA identified methylation mosaicism in an additional 15% and 11% of patients in the Chilean and Australian cohorts, respectively, suggesting the presence of a cryptic FM. Of these additional patients, 57% were confirmed to carry cryptic expanded alleles in blood, buccal mucosa, or saliva samples. Further confirmation was provided by identifying premutation (CGG 55-199) alleles in mothers of probands with methylation-sensitive Southern blot. Neurocognitive assessments showed that low-level mosaicism for cryptic FM alleles was associated with cognitive impairment or autism. CONCLUSIONS A substantial number of mosaic FM males who have cognitive impairment or autism are not diagnosed with the currently recommended 2-step testing protocol and can be identified with MS-QMA as a first-line test.

Barber-Say syndrome: further delineation of the clinical spectrum

We report on a 14-year-old girl who presented a multiple congenital anomaly pattern: ablepharon, hypertelorism, telecanthus, macrostomia, helix agenesis of both ears, redundant thick skin and severe hirsutism, the 5th reported case of Barber-Say syndrome. Our patient had almost the same phenotype as that of the patient cited by Martinez Santana et al. (Am. J. Med. Genet. 47: 20-23, 1993) including the same until then undescribed dermatoglyphic pattern.

Búsqueda de afecciones genéticas como etiología de déficit intelectual en individuos que asisten a escuelas de educación especial

Background: Mental retardation or intellectual disability affects 2% ofthe general population, but in 60% to 70% of cases the real cause ofthis retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak aareas and providing a genetic counseling to the family Aim: To search genetic diseases underiying intellectual disabilities of children attending a special education school. Material and methods: A clinical geneticist performed the history and physical examination in one hundred and three students aged between 5 and 24 years (51 males). A blood sample was obtained in 92 of them for a genetic screening that included a standard karyotype, fragile X molecular genetic testing and search for inborn errors of metabolism by tandem mass spectrometry. Results: This approach yielded an etiological diagnosis in as much as 29 patients. Three percent of them had a fragile X syndrome. Inborn errors of metabolism were not detected. Conclusions: This type of screening should be done always in children with intellectual disability to establish an etiological diagnosis.

Aspectos clínicos, moleculares y farmacológicos en los trastornos asociados a gen 1 del retraso mental del X frágil

BACKGROUND Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. DEVELOPMENT This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). CONCLUSIONS Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments.

Molecular classes in 209 patients with Prader–Willi or Angelman syndromes: Lessons for genetic counseling

Conflict of Interest: None Correspondence to: Dr. Vı́ctor Faundes, Laboratorio de Genética y Enfermedades Metabólicas, Instituto de Nutrición y Tecnologı́a de los Alimentos (INTA), Universidad de Chile, Av. El Lı́bano 5524, P.O. 7830490, Santiago, Chile. E-mail: vfaundes@inta.cl Article first published online in Wiley Online Library (wileyonlinelibrary.com): 6 October 2014 DOI 10.1002/ajmg.a.36801 TO THE EDITOR:

Distal 7q11.23 Duplication, an Emerging Microduplication Syndrome: A Case Report and Further Characterisation

Chromosome 7q11.23 duplication syndrome is a well-recognised syndrome which involves the duplication of the same genes located in the Williams-Beuren critical region. However, in 2010, 4 patients were reported with a microduplication only in the HIP1 and YWHAG genes. We refer to this as a distal 7q11.23 duplication (dup7q11.23D). Here, we report the fifth de novo patient with dup7q11.23D, whose symptoms may be explained by YWHAG overexpression as was demonstrated recently in mice and obese patients. Finally, further studies will be necessary to delineate this emerging microduplication syndrome.

Caracterización citogenético-molecular de enfermedades genéticas en el Hospital Base de Puerto Montt

Background Chromosome aberrations (CA) are the main etiology of multiple congenital malformations, recurrent abortions and intellectual disability (ID) specifically of moderate and severe degree. They account for 0.3 to 1% of newborns (NB) and 6 of 10,000 NB have chromosome imbalances with submicroscopic deletions or duplications smaller than 10 MB that are overlooked by conventional cytogenetic studies. Aim To report the results of cytogenetic and molecular studies performed in patients with a congenital malformation disease or ID with or without dysmorphic features, attended in a regional hospital. Patients and methods One hundred and eighty patients, 27 with a clinical diagnosis of Down syndrome, derived for the suspicion of a genetic disease, were studied. A karyogram was performed in all of them and in 30 cases additional molecular studies, such as fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR) were carried out. Results Among the 153 patients without Down syndrome, 20 (13%) had a genetic abnormality responsible for the altered phenotype. Sixteen had a chromosome aberration (structural and numerical aberrations in 75 and 25% respectively) and four had genetic molecular alterations. Additional studies were performed to confirm or better characterize the chromosome aberration in 13 of the 30 patients in whom these were requested. Conclusions Chromosome and specific genetic molecular studies in selected cases help to characterize patients with genetic diseases. The collaboration between academic and health care facilities is crucial.