RESUMEN
BACKGROUND: The majority of variants of unknown clinical significance (VUCS) in the CFTR gene are missense variants. While change on the CFTR protein structure or function is often suspected, impact on splicing may be neglected. Such undetected splicing default of variants may complicate the interpretation of genetic analyses and the use of an appropriate pharmacotherapy. METHODS: We selected 15 variants suspected to impact CFTR splicing after in silico predictions on 319 missense variants (214 VUCS), reported in the CFTR-France database. Six specialized laboratories assessed the impact of nucleotide substitutions on splicing (minigenes), mRNA expression levels (quantitative PCR), synthesis and maturation (western blot), cellular localization (immunofluorescence) and channel function (patch clamp) of the CFTR protein. We also studied maturation and function of the truncated protein, consecutive to in-frame aberrant splicing, on additional plasmid constructs. RESULTS: Six of the 15 variants had a major impact on CFTR splicing by in-frame (n = 3) or out-of-frame (n = 3) exon skipping. We reclassified variants into: splicing variants; variants causing a splicing defect and the impairment of CFTR folding and/or function related to the amino acid substitution; deleterious missense variants that impair CFTR folding and/or function; and variants with no consequence on the different processes tested. CONCLUSION: The 15 variants have been reclassified by our comprehensive approach of in vitro experiments that should be used to properly interpret very rare exonic variants of the CFTR gene. Targeted therapies may thus be adapted to the molecular defects regarding the results of laboratory experiments.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Humanos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/tratamiento farmacológico , Fibrosis Quística/genética , Exones , Empalme del ARN/genética , Mutación Missense , MutaciónRESUMEN
While the goals of genetic counseling for cystic fibrosis - delivering relevant information on the risk of recurrence and nondirectional support of couples at risk in their reproductive choices - have not changed fundamentally, the practice has evolved considerably in the last decade, growing more complex to face new challenges but also proving more effective. Many factors have contributed to this evolution: technical progress in the exploration of the genome (new generation sequencing) and in reproductive medicine, but also societal developments promoting access to genetic information and the professionalization of genetic counselors in France. The prospect of expanded pre-conception screening of at-risk couples makes genetic counselors major actors not only in medical care centers, but also in modern society by contributing to genetic education among citizens. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.
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Fibrosis Quística/diagnóstico , Fibrosis Quística/genética , Asesoramiento Genético , ADN/sangre , Femenino , Feto/metabolismo , Tamización de Portadores Genéticos , Humanos , Intercambio Materno-Fetal , Pruebas Prenatales no Invasivas , Atención Preconceptiva , Embarazo , Diagnóstico Preimplantación , Diagnóstico PrenatalRESUMEN
The autosomal recessive demyelinating form of Charcot-Marie-Tooth can be due to SH3TC2 gene pathogenic variants (CMT4C, AR-CMTde-SH3TC2). We report on a series of 13 patients with AR-CMTde-SH3TC2 among a French cohort of 350 patients suffering from all type of inheritance peripheral neuropathy. The SH3TC2 gene appeared to be the most frequently mutated gene for demyelinating neuropathy in this series by NGS. Four new pathogenic variants have been identified: two nonsense variants (p.(Tyr970*), p.(Trp1199*)) and two missense variants (p.(Leu1126Pro), p.(Ala1206Asp)). The recurrent variant p.Arg954* was present in 62%, and seems to be a founder mutation. The phenotype is fairly homogeneous, as all these patients, except the youngest ones, presented scoliosis and/or hearing loss.
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Enfermedad de Charcot-Marie-Tooth/genética , Sordera/genética , Variación Genética/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Escoliosis/genética , Adulto , Anciano , Enfermedad de Charcot-Marie-Tooth/epidemiología , Niño , Estudios de Cohortes , Sordera/epidemiología , Femenino , Francia/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Mutación/genética , Escoliosis/epidemiología , Adulto JovenRESUMEN
Fragile X syndrome is the most usual cause of hereditary intellectual deficiency. Typical symptoms combine intellectual deficiency, social anxiety, intense emotional vigilance, and a characteristic facial dysmorphy. This is subsequent to a complete mutation of the FMR1 gene, considering a semidominant transmission linked to the unstable X. The expansion of the CGG triplet greater than 200 units combined with a high methylation pattern lead to a transcriptional silence of the FMR1 gene, and the protein product, the FMRP, is not synthesized. This protein is involved in synaptic plasticity. Brain MRI can show an increased volume of the caudate nucleus and hippocampus, combined with hypoplasia of the cerebellar vermis. Fragile X Associated Tremor Ataxia Syndrome (FXTAS) syndrome is a neurodegenerative disorder occurring in carriers of the premutation in FMR1. Brain MRI shows an increased T2 signal in the middle cerebellar peduncles. This syndrome is linked to a premutation in the FMR1 gene. We report here the case of two brothers presenting a typical fragile X symptomatology. Brain MRI showed hyperintensities of the middle cerebellar peduncles. Such MRI findings support the assumption of a genetic mosaicism.
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Síndrome del Cromosoma X Frágil/diagnóstico , Síndrome del Cromosoma X Frágil/genética , Sustancia Blanca/anomalías , Encéfalo/patología , Preescolar , Análisis Mutacional de ADN , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Tamización de Portadores Genéticos , Humanos , Imagen por Resonancia Magnética , Masculino , Mosaicismo , Fenotipo , Expansión de Repetición de Trinucleótido/genéticaRESUMEN
BACKGROUND: Analysis of cell-free foetal DNA (cff-DNA) in maternal plasma is very promising for early diagnosis of monogenic diseases; in particular, cystic fibrosis (CF). However, NIPD of single-gene disorders has been limited by the availability of suitable technical platforms and the need to set up patient or disease-specific custom-made approaches. METHODS: To make research applications more readily accessible to the clinic, we offer a simple assay combining two independent methods to determine the presence or absence of paternally inherited foetal allele p.Phe508del (the most frequent mutation in CF patients worldwide). The first method detects the presence or absence of a p.Phe508del allele by Mutant Enrichment with 3'-Modified Oligonucleotide PCR coupled to Fragment Length Analysis (MEMO-PCR-FLA). The second method detects the p.Phe508del allele with classical Multiplex Fluorescent PCR including five intragenic and extragenic STR markers of the CFTR locus and a specific SRY sequence. RESULTS: We collected 24 plasma samples from 23 women carrying foetuses at risk for CF and tested each sample using both methods. Our new procedures were successfully applied to 10 couples where fathers carried the p.Phe508del mutation and mothers were carrying a different mutation in the CFTR gene. These simple tests provided clear positive or negative results from the maternal plasma of the pregnant women. We confirmed the presence of cff-DNA in the studied samples by the identification of a tri-allelic DNA profile using a miniSTR kit. All results were correlated with chorionic villus sampling or amniocentesis analyses. CONCLUSIONS: This NIPD approach, easily set up in any clinical laboratory where prenatal diagnosis is routinely performed, offers many advantages over current methods: it is simple, rapid, and cost-effective. It opens up the possibility for testing a large number of couples with offspring at risk for CF.
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Amniocentesis/métodos , Muestra de la Vellosidad Coriónica/métodos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística , Reacción en Cadena de la Polimerasa/métodos , Adulto , Investigación sobre la Eficacia Comparativa , Fibrosis Quística/sangre , Fibrosis Quística/diagnóstico , Fibrosis Quística/genética , Electroforesis Capilar/métodos , Femenino , Humanos , Mutación , Embarazo , Diagnóstico Prenatal/métodos , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: Prader-Willi syndrome (PWS) is a developmental genetic disorder characterised by a variable expression of medical, cognitive and behavioural symptoms. In adulthood, the prevalence and severity of these symptoms determine the quality of life of the affected persons. Because of their rare disease condition, data on health and social problems in adults with PWS are scarce. In this research, we present medical, psychological and social features of a large cohort of adults admitted to a specialised PWS centre in France and analyse the differences according to genotype, gender and age. METHODS: Data from 154 patients (68 men/86 women), with a median age of 27 years (range 16-54), were collected during their stay in our centre. Clinical histories were completed using information from parents or main caregivers, and the same medical team performed the diagnosis of different clinical conditions. Statistical analyses were performed to determine the influence of factors such as genotype, age or gender. RESULTS: Paternal deletion genotype was the most frequent (65%) at all ages. Most patients had mild or moderate intellectual disability (87%). Only 30% had studied beyond primary school and 70% were in some special educational or working programme. Most of them lived in the family home (57%). The most prevalent somatic comorbidities were scoliosis (78%), respiratory problems (75%), dermatological lesions (50%), hyperlipidaemia (35%), hypothyroidism (26%), Type 2 diabetes mellitus (25%) and lymph oedema (22%). Some form of psychotropic treatment was prescribed in 58% of subjects, and sex hormones in 43%. Patients with deletion had a higher body mass index (44 vs. 38.9 kg/m(2)) and displayed higher frequency of sleep apnoeas. Non-deletion patients received insulin treatment (19% vs. 4%) and antipsychotic treatment (54.8% vs. 32.7%) more frequently. No difference was observed in the prevalence of Type 2 diabetes between the two genotype groups. Patients >27 years of age had a higher rate of comorbidities (Type 2 diabetes, hypertension, respiratory problems and lymph oedema). Gender differences were minor. CONCLUSIONS: Adult patients with PWS showed high prevalence of comorbid health problems that need to be monitored for early treatment. Some of them are influenced by genotype and age. Another salient problem concerns the lack of adapted structures for better social integration. Further data about the real life and health conditions of adults with PWS are necessary to further our knowledge of the natural history of the disease and to design appropriate care strategies.
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Síndrome de Prader-Willi , Adolescente , Adulto , Estudios de Cohortes , Comorbilidad , Femenino , Francia/epidemiología , Hospitales Especializados/estadística & datos numéricos , Humanos , Masculino , Persona de Mediana Edad , Síndrome de Prader-Willi/epidemiología , Síndrome de Prader-Willi/genética , Síndrome de Prader-Willi/fisiopatología , Síndrome de Prader-Willi/psicología , Adulto JovenRESUMEN
Van der Woude syndrome is known to be the first syndromic cause of oral cleft. Apart clefts the cardinal signs are lower lip pits and hypodontia. IRF6 gene mutations have been recently identified as potential cause in this syndrome which permits to better understand its phenotype heterogeneity. Based on a literature review, we tried to cover the different aspects of this syndrome with an emphasis on genetic counselling and surgical correction of lip pits.
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Anomalías Múltiples , Labio Leporino , Fisura del Paladar , Quistes , Labio/anomalías , Anomalías Múltiples/diagnóstico , Anomalías Múltiples/cirugía , Labio Leporino/diagnóstico , Labio Leporino/cirugía , Fisura del Paladar/diagnóstico , Fisura del Paladar/cirugía , Quistes/diagnóstico , Quistes/cirugía , Humanos , Lactante , Labio/cirugía , Masculino , FenotipoRESUMEN
BACKGROUND: Branchio-Oculo-Facial Syndrome (BOFS, MIM#113620) is a rare, polymalformational disorder with cutaneous and ocular abnormalities and characteristic facial anomalies. It is an autosomal dominant developmental disorder caused by mutations or deletions in the transcription factor AP-2 alpha gene (TFAP2A, 6p24). We report a new case of atypical BOFS with a unilateral cervical cutaneous defect. PATIENT AND METHODS: A 5-year-old girl was admitted to our dermatology department for a congenital, linear, erythematous cutaneous anomaly on the right side of her neck. There was no family history. She also presented characteristic facial and ocular anomalies. BOFS was suspected. TFAP2A molecular analysis revealed a heterozygous missense mutation c.767C>T (p.Ala256Val). DISCUSSION: BOFS is variable and remains unknown to dermatologists in spite of distinctive cutaneous features. Identification of this syndrome is important to improving medical care (multidisciplinary care, further tests, genetic counselling). We report a case of atypical BOFS with a unilateral cervical cutaneous defect in one patient and bilateral cutaneous anomalies in the other four patients. In agreement with the literature, there did not appear to be mutation-specific genotype-phenotype correlations.
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Síndrome Branquio Oto Renal , Síndrome Branquio Oto Renal/diagnóstico , Preescolar , Femenino , Humanos , FenotipoRESUMEN
Twenty-five novel mutations including duplications in the ATP7A gene. Menkes disease (MD) and occipital horn syndrome (OHS) are allelic X-linked recessive copper deficiency disorders resulting from ATP7A gene mutations. MD is a severe condition leading to progressive neurological degeneration and death in early childhood, whereas OHS has a milder phenotype with mainly connective tissue abnormalities. Until now, molecular analyses have revealed only deletions and point mutations in both diseases. This study reports new molecular data in a series of 40 patients referred for either MD or OHS. We describe 23 point mutations (9 missense mutations, 7 splice site variants, 4 nonsense mutations, and 3 small insertions or deletions) and 7 intragenic deletions. Of these, 18 point mutations and 3 deletions are novel. Furthermore, our finding of four whole exon duplications enlarges the mutation spectrum in the ATP7A gene. ATP7A alterations were found in 85% of cases. Of these alterations, two thirds were point mutations and the remaining one third consisted of large rearrangements. We found that 66.6% of point mutations resulted in impaired ATP7A transcript splicing, a phenomenon more frequent than expected. This finding enabled us to confirm the pathogenic role of ATP7A mutations, particularly in missense and splice site variants.
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Adenosina Trifosfatasas/genética , Proteínas de Transporte de Catión/genética , Cutis Laxo/genética , Síndrome de Ehlers-Danlos/genética , Duplicación de Gen/genética , Síndrome del Pelo Ensortijado/genética , Mutación Puntual/genética , Eliminación de Secuencia/genética , ATPasas Transportadoras de Cobre , Cutis Laxo/patología , Síndrome de Ehlers-Danlos/patología , Exones/genética , Femenino , Perfilación de la Expresión Génica , Reordenamiento Génico/genética , Humanos , Masculino , Síndrome del Pelo Ensortijado/patología , Reacción en Cadena de la Polimerasa Multiplex , Mutación Missense/genética , Sitios de Empalme de ARN/genéticaRESUMEN
The oral-facial-digital syndrome type I (OFD I) is characterized by multiple congenital malformations of the face, oral cavity and digits. A polycystic kidney disease (PKD) is found in about one-third of patients but long-term outcome and complications are not well described in the international literature. Renal findings have been retrospectively collected in a cohort of 34 females all carrying a pathogenic mutation in the OFD1 gene with ages ranging from 1 to 65 years. Twelve patients presented with PKD - 11/16 (69%) if only adults were considered -with a median age at diagnosis of 29 years [IQR (interquartile range) = (23.5-38)]. Among them, 10 also presented with renal impairment and 6 were grafted (median age = 38 years [IQR = (25-48)]. One grafted patient under immunosuppressive treatment died from a tumor originated from a native kidney. The probability to develop renal failure was estimated to be more than 50% after the age of 36 years. Besides, neither genotype-phenotype correlation nor clinical predictive association with renal failure could be evidenced. These data reveal an unsuspected high incidence rate of the renal impairment outcome in OFD I syndrome. A systematic ultrasound (US) and renal function follow-up is therefore highly recommended for all OFD I patients.
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Envejecimiento , Síndromes Orofaciodigitales/complicaciones , Insuficiencia Renal/etiología , Adolescente , Adulto , Niño , Preescolar , Estudios de Cohortes , Femenino , Estudios de Asociación Genética , Humanos , Lactante , Riñón/patología , Persona de Mediana Edad , Síndromes Orofaciodigitales/genética , Síndromes Orofaciodigitales/patología , Síndromes Orofaciodigitales/fisiopatología , Proteínas/genética , Adulto JovenRESUMEN
Microcephalic osteodysplastic primordial dwarfism type II (MOPD II, MIM 210720) and Seckel syndrome (SCKL, MIM 210600) belong to the primordial dwarfism group characterised by intrauterine growth retardation, severe proportionate short stature, and pronounced microcephaly. MOPD II is distinct from SCKL by more severe growth retardation, radiological abnormalities, and absent or mild mental retardation. Seckel syndrome is associated with defective ATR dependent DNA damage signalling. In 2008, loss-of-function mutations in the pericentrin gene (PCNT) have been identified in 28 patients, including 3 SCKL and 25 MOPDII cases. This gene encodes a centrosomal protein which plays a key role in the organisation of mitotic spindles. The aim of this study was to analyse PCNT in a large series of SCKL-MOPD II cases to further define the clinical spectrum associated with PCNT mutations. Among 18 consanguineous families (13 SCKL and 5 MOPDII) and 6 isolated cases (3 SCKL and 3 MOPD II), 13 distinct mutations were identified in 5/16 SCKL and 8/8 MOPDII including five stop mutations, five frameshift mutations, two splice site mutations, and one apparent missense mutation affecting the last base of exon 19. Moreover, we demonstrated that this latter mutation leads to an abnormal splicing with a predicted premature termination of translation. The clinical analysis of the 5 SCKL cases with PCNT mutations showed that they all presented minor skeletal changes and clinical features compatible with MOPDII diagnosis. It is therefore concluded that, despite variable severity, MOPDII is a genetically homogeneous condition due to loss-of-function of pericentrin.
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Antígenos/genética , Estudios de Cohortes , Consanguinidad , Enanismo/diagnóstico por imagen , Enanismo/genética , Familia , Femenino , Ligamiento Genético , Sitios Genéticos/genética , Genotipo , Crecimiento y Desarrollo/genética , Mano/diagnóstico por imagen , Cadera/diagnóstico por imagen , Humanos , Pierna/diagnóstico por imagen , Masculino , Microcefalia/diagnóstico por imagen , Microcefalia/genética , Mutación/genética , RadiografíaRESUMEN
BACKGROUND: Cystic fibrosis (CF) is caused by compound heterozygosity or homozygosity of CF transmembrane conductance regulator gene (CFTR) mutations. Phenotypic variability associated with certain mutations makes genetic counselling difficult, notably for R117H, whose disease phenotype varies from asymptomatic to classical CF. The high frequency of R117H observed in CF newborn screening has also introduced diagnostic dilemmas. The aim of this study was to evaluate the disease penetrance for R117H in order to improve clinical practice. METHODS: The phenotypes in all individuals identified in France as compound heterozygous for R117H and F508del, the most frequent CF mutation, were described. The allelic prevalences of R117H (p(R117H)), on either intron 8 T5 or T7 background, and F508del (p(F508del)) were determined in the French population, to permit an evaluation of the penetrance of CF for the [R117H]+[F508del] genotype. RESULTS: Clinical details were documented for 184 [R117H]+[F508del] individuals, including 72 newborns. The disease phenotype was predominantly mild; one child had classical CF, and three adults' severe pulmonary symptoms. In 5245 healthy adults, p(F508del) was 1.06%, p(R117H;T7) 0.27% and p(R117H;T5)<0.01%. The theoretical number of [R117H;T7]+[F508del] individuals in the French population was estimated at 3650, whereas only 112 were known with CF related symptoms (3.1%). The penetrance of classical CF for [R117H;T7]+[F508del] was estimated at 0.03% and that of severe CF in adulthood at 0.06%. CONCLUSIONS: These results suggest that R117H should be withdrawn from CF mutation panels used for screening programmes. The real impact of so-called disease mutations should be assessed before including them in newborn or preconceptional carrier screening programmes.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Asesoramiento Genético , Heterocigoto , Tamizaje Neonatal , Penetrancia , Estudios Transversales , Fibrosis Quística/diagnóstico , Fibrosis Quística/epidemiología , Humanos , Recién Nacido , Estimación de Kaplan-Meier , Mutación , FenotipoAsunto(s)
Encefalopatías Metabólicas/enzimología , Encefalopatías Metabólicas/genética , Epilepsia/enzimología , Epilepsia/genética , Predisposición Genética a la Enfermedad/genética , Proteínas Serina-Treonina Quinasas/genética , Edad de Inicio , Sustitución de Aminoácidos/genética , Encefalopatías Metabólicas/fisiopatología , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Preescolar , Estudios de Cohortes , Análisis Mutacional de ADN , Discapacidades del Desarrollo/enzimología , Discapacidades del Desarrollo/genética , Discapacidades del Desarrollo/fisiopatología , Progresión de la Enfermedad , Epilepsia/fisiopatología , Femenino , Marcadores Genéticos/genética , Pruebas Genéticas , Genotipo , Humanos , Masculino , Trastornos del Movimiento/enzimología , Trastornos del Movimiento/genética , Trastornos del Movimiento/fisiopatología , Hipotonía Muscular/etiología , Hipotonía Muscular/fisiopatología , Mutación/genética , Polimorfismo de Nucleótido Simple/genéticaRESUMEN
BACKGROUND: Smith-Lemli-Opitz syndrome (SLOS) (MIM 270 400) is an autosomal recessive multiple congenital anomalies/mental retardation syndrome caused by mutations in the Delta7-sterol reductase (DHCR7, E.C.1.3.1.21) gene. The prevalence of SLOS has been estimated to range between 1:15000 and 1:60000 in populations of European origin. METHODS AND RESULTS: We have analysed the frequency, origin, and age of DHCR7 mutations in European populations. In 263 SLOS patients 10 common alleles (c.964-1G>C, p.Trp151X, p.Thr93Met, p.Val326Leu, p.Arg352Trp, p.Arg404Cys, p.Phe302Leu, p.Leu157Pro, p.Gly410Ser, p.Arg445Gln) were found to constitute approximately 80% of disease-causing mutations. As reported before, the mutational spectra differed significantly between populations, and frequency peaks of common mutations were observed in North-West (c.964-1G>C), North-East (p.Trp151X, p.Val326Leu) and Southern Europe (p.Thr93Met). SLOS was virtually absent from Finland. The analysis of nearly 8000 alleles from 10 different European populations confirmed a geographical distribution of DHCR7 mutations as reported in previous studies. The common Null mutations in Northern Europe (combined ca. 1:70) occurred at a much higher frequency than expected from the reported prevalence of SLOS. In contrast the most common mutation in Mediterranean SLOS patients (p.Thr93Met) had a low population frequency. Haplotypes were constructed for SLOS chromosomes, and for wild-type chromosomes of African and European origins using eight cSNPs in the DHCR7 gene. The DHCR7 orthologue was sequenced in eight chimpanzees (Pan troglodytes) and three microsatellites were analysed in 50 of the SLOS families in order to estimate the age of the three major SLOS-causing mutations. CONCLUSIONS: The results indicate a time of first appearance of c.964-1G>C and p.Trp151X some 3000 years ago in North-West and North-East Europe, respectively. The p.Thr93Met mutations on the J haplotype has probably first arisen approximately 6000 years ago in the Eastern Mediterranean. Together, it appears that a combination of founder effects, recurrent mutations, and drift have shaped the present frequency distribution of DHCR7 mutations in Europe.
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Evolución Molecular , Mutación , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/genética , Síndrome de Smith-Lemli-Opitz/genética , Alelos , Animales , Secuencia de Bases , Cartilla de ADN/genética , Europa (Continente) , Efecto Fundador , Genética de Población , Haplotipos , Humanos , Pan troglodytes/genética , Polimorfismo de Nucleótido Simple , Síndrome de Smith-Lemli-Opitz/enzimologíaRESUMEN
The p.Val754Met variant, described in 1996 in a CF patient, has been considered a CF mutation. However, biochemical aspects, results of functional studies and, finally, the identification of a complex deletion removing exons 3 to 10 and 14b to 16 in cis of p.Val754Met in a CF patient, argue against a strong deleterious effect. An inventory through the French CF network of patients carrying p.Val754Met led to the registration of seven patients (CF: n=4; idiopathic chronic pancreatitis: n=3) and six healthy individuals, all heterozygous for the variation. Extensive CFTR gene analysis was carried out, including the search for large rearrangements and other possible mutations. The complex deletion, whose breakpoints are described here, was found only in the four CF patients, in association with the same haplotype. This data, added to the fact that the p.[Phe508del]+[Val754Met] genotype was found in a healthy individual, bring further arguments against the association of p.Val754Met with CF. We thus suggest looking for a possible complex allele whenever p.Val754Met is detected and considering it neutral regarding genetic counseling when found in isolation.
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Alelos , Aberraciones Cromosómicas , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Adolescente , Adulto , Secuencia de Bases , Niño , Fibrosis Quística/diagnóstico , Análisis Mutacional de ADN , Femenino , Pruebas Genéticas , Haplotipos , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Mutación Missense , Polimorfismo Genético , Eliminación de SecuenciaRESUMEN
Oral-facial-digital syndrome type 1 (OFD1) is characterised by an X linked dominant mode of inheritance with lethality in males. Clinical features include facial dysmorphism with oral, tooth, and distal abnormalities, polycystic kidney disease, and central nervous system malformations. Large interfamilial and intrafamilial clinical variability has been widely reported, and 18 distinct mutations have been previously reported within OFD1. A French and Belgian collaborative study collected 25 cases from 16 families. OFD1 was analysed using direct sequencing and phenotype-genotype correlation was performed using chi2 test. X inactivation studies were performed on blood lymphocytes. In 11 families, 11 novel mutations, including nine frameshift, one nonsense, and one missense mutation were identified, which spanned nine different exons. A combination of our results with previously reported cases showed that the majority of mutations (65.5%) was located in exons 3, 8, 9, 13, and 16. There was phenotype-genotype correlation between (a) polycystic kidney disease and splice mutations; (b) mental retardation and mutations located in exons 3, 8, 9, 13, and 16; and (c) tooth abnormalities and mutations located in coiled coil domains. Comparing the phenotype of the families with a pathogenic mutation to families with absence of OFD1 mutation, polycystic kidneys and short stature were significantly more frequent in the group with no OFD1 mutation, whereas lingual hamartomas were significantly more frequent in the group with OFD1 mutation. Finally, an X inactivation study showed non-random X inactivation in a third of the samples. Differential X inactivation between mothers and daughters in two families with high intrafamilial variability was of particular interest. Slight phenotype-genotype correlations were established, and X inactivation study showed that skewed X inactivation could be partially involved in the pathogenesis of intrafamilial clinical variability.
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Síndromes Orofaciodigitales/genética , Síndromes Orofaciodigitales/patología , Proteínas/genética , Adulto , Bélgica , Análisis Mutacional de ADN , Femenino , Francia , Ligamiento Genético , Genotipo , Humanos , Mutación/genética , Linaje , Fenotipo , Inactivación del Cromosoma X/genéticaRESUMEN
The Albright hereditary osteodystrophy-like (AHO-like) syndrome was recently defined as a rare dysmorphic syndrome including brachymetaphalangism and mental retardation. This phenotype occurs in Albright hereditary osteodystrophy (AHO) but unlike it, the level of the Gs alpha protein activity is not reduced. To date 59 patients with these clinical and biochemical features have been reported, and for the majority of them (57/59) a cytogenetically visible 2q37 deletion has been observed. We report a new case of typical AHO-like syndrome with normal karyotype. Using the polymorphic marker D2S125 we found a loss of heterozygosity suggestive of a de novo 2q37 deletion of maternal origin. This hypothesis was confirmed by FISH analysis with a subtelomeric 2q probe containing the D2S90 marker. Genotypic analysis allowed us to map the proximal breakpoint of the subtelomeric deletion within an interval delimited by D2S2338 (present) and D2S2253 (deleted). This 2q subtelomeric deletion as small as 4 Mb is to date the smallest one observed in association with a typical AHO-like phenotype, and allows us to move the centromeric boundary of the AHO-like critical region by 750 kb towards the 2q telomere.
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Deleción Cromosómica , Cromosomas Humanos Par 2 , Displasia Fibrosa Poliostótica/genética , Adolescente , Análisis Citogenético , Femenino , Humanos , Cariotipificación , Repeticiones de Microsatélite , Linaje , FenotipoRESUMEN
Spinal muscular atrophy (SMA) is caused by SMN1 gene deletions or mutations, and ALS is the most frequent motor neuron condition in adults. The authors describe three families in which ALS and SMA coexist. The authors found that no SOD1 mutation was found within these families; all three ALS cases had at least two SMN1 copies; and an abnormal SMN1 gene locus did not explain the co-occurrence of these two motor neuron disorders in these families.