[Genetic diffuse cystic lung disease in adults]. / Maladies kystiques pulmonaires de l'adulte d'origine génétique.

Multiple cystic lung diseases comprise a wide range of various diseases, some of them of genetic origin. Lymphangioleiomyomatosis (LAM) is a disease occurring almost exclusively in women, sporadically or in association with tuberous sclerosis complex (TSC). Patients with LAM present with lymphatic complications, renal angiomyolipomas and cystic lung disease responsible for spontaneous pneumothoraces and progressive respiratory insufficiency. TSC and LAM have been ascribed to mutations in TSC1 or TSC2 genes. Patients with TSC are variably affected by cutaneous, cognitive and neuropsychiatric manifestations, epilepsy, cerebral and renal tumors, usually of benign nature. Birt-Hogg-Dubé syndrome is caused by mutations in FLCN encoding folliculin. This syndrome includes lung cysts of basal predominance, cutaneous fibrofolliculomas and various renal tumors. The main complications are spontaneous pneumothoraces and renal tumors requiring systematic screening. The mammalian target of rapamycin (mTOR) pathway is involved in the pathophysiology of TSC, sporadic LAM and Birt-Hogg-Dubé syndrome. MTOR inhibitors are used in LAM and in TSC while Birt-Hogg-Dubé syndrome does not progress towards chronic respiratory failure. Future challenges in these often under-recognized diseases include the need to reduce the delay to diagnosis, and to develop potentially curative treatments. In France, physicians can seek help from the network of reference centers for the diagnosis and management of rare pulmonary diseases.

Tuberous Sclerosis Complex: Genetic counselling and perinatal follow-up.

Tuberous sclerosis is an autosomal dominant disorder almost fully penetrant with highly variable expression. Most cases are de novo and this diagnosis is sometimes considered during prenatal life in case of cardiac tumor, unique or multiple. The couple should be referred to a specialized tertiary prenatal care center for expertise and information. Fetal molecular testing of the two genes TSC1 and TSC2 is often informative. Prognosis determination for Tuberous Sclerosis remains a difficult task. Cardiac tumors can be sometimes worrying but only a minority will have a pejorative issue and most cases are asymptomatic without any therapeutic intervention needed. Only few cases need surgical or medical treatment. Patients with Tuberous Sclerosis can develop skin, eye, kidney or lung lesions later on, but they are either of limited consequence or treatable. The crux of the matter is the neurological involvement with frequent intellectual deficiency and epilepsy that can be drug-resistant. The absence of lesion on fetal brain MRI is not predictive of any prognosis and does not rule out Tuberous Sclerosis. De novo TSC2 mutation is a negative prognosis factor and conversely, an inherited TSC1 mutation is a more favorable one, but with a severe issue still possible. Facing this cautious prognosis, some couple may opt for termination of pregnancy while others decide to pursue it. It is then fundamental to set cardiac and neurological regular follow-up for these newborns. © 2022 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Lethal form of spinocerebellar ataxia type 7 with early onset in childhood.

Progressive cerebellar ataxias are well-known hereditary neurological disorders. Among them, spinocerebellar ataxia type 7 (SCA7) is inherited as an autosomal dominant trait and is ascribed to the expansion of a CAG trinucleotide repeat within the ATXN7 gene. An anticipation phenomenon can occur during paternal transmission and sometimes is responsible for a severe infantile form. The specificity of SCA7 is the retinal involvement with retinitis pigmentosa and cone rod dystrophy. We describe a familial form with two siblings who died of a severe infantile form. Diagnosis was made in their father, who had a recent history of macular atrophy and presented with gait disturbance thereafter. Retrospectively, substantial triplet repeat expansion was confirmed in the two affected infants. These infantile forms are rare and difficult to diagnose in the absence of suggestive family symptoms.

Combined genetic approaches yield a 48% diagnostic rate in a large cohort of French hearing-impaired patients.

Hearing loss is the most common sensory disorder and because of its high genetic heterogeneity, implementation of Massively Parallel Sequencing (MPS) in diagnostic laboratories is greatly improving the possibilities of offering optimal care to patients. We present the results of a two-year period of molecular diagnosis that included 207 French families referred for non-syndromic hearing loss. Our multi-step strategy involved (i) DFNB1 locus analysis, (ii) MPS of 74 genes, and (iii) additional approaches including Copy Number Variations, in silico analyses, minigene studies coupled when appropriate with complete gene sequencing, and a specific assay for STRC. This comprehensive screening yielded an overall diagnostic rate of 48%, equally distributed between DFNB1 (24%) and the other genes (24%). Pathogenic genotypes were identified in 19 different genes, with a high prevalence of GJB2, STRC, MYO15A, OTOF, TMC1, MYO7A and USH2A. Involvement of an Usher gene was reported in 16% of the genotyped cohort. Four de novo variants were identified. This study highlights the need to develop several molecular approaches for efficient molecular diagnosis of hearing loss, as this is crucial for genetic counselling, audiological rehabilitation and the detection of syndromic forms.

Homozygous PKP2 deletion associated with neonatal left ventricle noncompaction.

Left ventricular noncompaction cardiomyopathy (LVNC) is a clinically heterogeneous disorder characterized by a trabecular meshwork and deep intertrabecular myocardial recesses that communicate with the left ventricular cavity. Several genetic causes of LVNC have been reported, with variable modes of inheritance, including autosomal dominant and X-linked inheritance, but relatively few responsible genes have been identified. A NGS workflow, based on a panel of 95 genes developed for sequencing most prevalent sudden cardiac death-causing genes, was used to make a rapid and costless molecular diagnosis in two siblings with a severe noncompaction cardiomyopathy starting prenatally and leading to rapid cardiac failure. For the first time, a total homozygous PKP2 deletion was identified. This molecular defect was further confirmed by MLPA and array-comparative genomic hybridization (CGH). Heterozygous PKP2 mutations are usually reported in a significant proportion of Arrhythmogenic Right Ventricular Cardiomyopathy cases. Our results show, for the first time, the involvement of PKP2 in severe cardiomyopathy with ventricular non compaction.

[The complex phenotype of ARC syndrome: A new case]. / Le phénotype complexe du syndrome ARC : une nouvelle observation.

ARC syndrome (arthrogryposis - renal dysfunction - cholestasis) is a rare lethal multisystemic autosomal recessive disease. A newborn of consanguineous parents of Algerian descent presented cholestatic jaundice, dehydration, and Fanconi syndrome at 10 days of life. The blood smear showed a very characteristic gray appearance of platelets. A homozygous mutation was evidenced in the VPS33B gene. This gene codes for a protein involved in trafficking of intracellular vesicles. The mutation (c.604-2A>G) present in the heterozygous state in the parents affects an invariant base of the splice acceptor site and to our knowledge has not been reported yet. This child died at the age of 3 months. Prenatal diagnosis was offered to the family; another pregnancy was carried to completion and a girl was born without the disease. The combination of cholestasis and proximal tubulopathy should suggest the diagnosis in a newborn with orthopedic problems. A blood smear greatly facilitates diagnosis.

Xq28 duplication including MECP2 in six unreported affected females: what can we learn for diagnosis and genetic counselling?

Duplication of the Xq28 region, involving MECP2 (dupMECP2), has been primarily described in males with severe developmental delay, spasticity, epilepsy, stereotyped movements and recurrent infections. Carrier mothers are usually asymptomatic with an extremely skewed X chromosome inactivation (XCI) pattern. We report a series of six novel symptomatic females carrying a de novo interstitial dupMECP2, and review the 14 symptomatic females reported to date, with the aim to further delineate their phenotype and give clues for genetic counselling. One patient was adopted and among the other 19 patients, seven (37%) had inherited their duplication from their mother, including three mildly (XCI: 70/30, 63/37, 100/0 in blood and random in saliva), one moderately (XCI: random) and three severely (XCI: uninformative and 88/12) affected patients. After combining our data with data from the literature, we could not show a correlation between XCI in the blood or duplication size and the severity of the phenotype, or explain the presence of a phenotype in these females. These findings confirm that an abnormal phenotype, even severe, can be a rare event in females born to asymptomatic carrier mothers, making genetic counselling difficult in couples at risk in terms of prognosis, in particular in prenatal cases.

Heterozygous CLCN1 mutations can modulate phenotype in sodium channel myotonia.

Nondystrophic myotonias are characterized by muscle stiffness triggered by voluntary movement. They are caused by mutations in either the CLCN1 gene in myotonia congenita or in the SCN4A gene in paramyotonia congenita and sodium channel myotonias. Clinical and electrophysiological phenotypes of these disorders have been well described. No concomitant mutations in both genes have been reported yet. We report five patients from three families showing myotonia with both chloride and sodium channel mutations. Their clinical and electrophysiological phenotypes did not fit with the phenotype known to be associated with the mutation initially found in SCN4A gene, which led us to screen and find an additional mutation in CLCN1 gene. Our electrophysiological and clinical observations suggest that heterozygous CLCN1 mutations can modify the clinical and electrophysiological expression of SCN4A mutation.

Genetic variation in TGFB1 gene and risk of idiopathic recurrent pregnancy loss.

Transforming growth factor ß1 plays a significant role in pregnancy outcome. We investigated the association of TGFB1 exon 1 (rs1800471, rs1800470) and promoter region (rs1800469, rs1800468) polymorphisms with recurrent pregnancy loss (RPL) in 675 Tunisian women: 304 women with a history of three consecutive pregnancy losses of unknown etiology with the same partner and 371 age-matched multiparous control women. TGFB1 genotyping was done by TaqMan assays. Higher minor allele frequency for rs1800471 (P< 0.001), but not for rs1800470, rs1800469 or rs1800468 was found in RPL cases compared with controls. A significant difference in the distribution of rs1800471 genotypes was seen between the RPL cases and control women, irrespective of the genetic model used. Increased RPL risk was seen with rs1800471 allele C in the heterozygous state and to a greater degree in the homozygous state, thus establishing a dose-dependent effect. Haploview analysis revealed differential linkage disequilibrium between the TGFB1 single-nucleotide polymorphisms analyzed. TGFB1 haplotype analysis identified eight common haplotypes (rs1800471/rs1800470/rs1800469/rs1800468) with three (GTTG, Pc = 0.02; CCTG, Pc = 0.02 and CTCG, Pc = 0.02) positively associated with RPL and one (GCCG, Pc = 0.009) negatively associated with RPL. This study provides the first evidence that the TGFB1 genotype may influence RPL.

[Pregnancy and Ehlers-Danlos vascular syndrome: patients' care and complications]. / Grossesse et syndrome d'Ehlers-Danlos vasculaire : prise en charge et complications.

INTRODUCTION: Elhers-Danlos vascular syndrome type IV (EDS4) is a hereditary pathology of the connective tissue responsible for an increased risk of lethal arterial, uterine and digestive complications during and after pregnancy. PATIENTS AND METHODS: We describe the obstetrical care, the nature and frequency of complications related to pregnancy of patients with EDS4 and their relatives. RESULTS: Twenty-seven pregnancies were studied including 23 deliveries, 18 vaginal deliveries and five caesarean, no maternal death and two major life-threatening complications (8.7%) were recorded which could be directly linked to EDS4 (rupture of the biscupid valve pillar after vaginal delivery and a rupture of the caecum after a prophylactic caesarean). Ten deliveries underwent epidural anesthesia without complication. Six perineal injuries (33.3%) were observed. CONCLUSION: Pregnancy in patient with EDS4 needs obstetrical cares in a special unit's motivated medical team with intensive care and surgical disponibilities.

Identification of specific vascular endothelial growth factor susceptible and protective haplotypes associated with recurrent spontaneous miscarriages.

BACKGROUND: We investigated the association of vascular endothelial growth factor (VEGF) gene polymorphism with recurrent spontaneous miscarriage (RSM). METHODS: VEGF -2578C/A, -1154G/A, -634G/C, +936C/T single nucleotide polymorphisms (SNPs) were assessed in 304 RSM patients, and 371 age-and body mass index-matched control subjects using real-time PCR. RESULTS: Higher minor allele frequency of -1154G/A (P < 0.001) and +936C/T (P < 0.001), but not -2578C/A (P = 0.55) or -634G/C (P = 0.87) SNPs, were seen in patients. Significant differences in the distribution of -1154G/A (P = 0.006) and +936C/T (P = 0.015), but not -2578C/A (P = 0.473) or -634G/C (P = 1.000) genotypes, were seen in cases compared with control women. Of the possible 16 VEGF haplotypes, 9 were found to be common, and were included. A significantly lower frequency of C G C C (P = 0.008), and A G G C (P < 0.001) haplotypes, and a higher frequency C G C T (P = 0.020), and C G T (P = 0.004) haplotypes were seen in patients. CONCLUSIONS: These results strongly support that VEGF polymorphisms, in particular-1154G/A and +936C/T, are significantly associated with RSM. Our results confirm, in the largest sample to date, previous works in other populations on VEGF polymorphism in RSM.

Binder phenotype in mothers affected with autoimmune disorders.

OBJECTIVE: To report four foetal cases of the Binder phenotype associated with maternal autoimmune disorders. PATIENTS AND METHODS: In three mothers with autoimmune diseases, 2D and 3D ultrasonographic measurements were made on four foetuses with the Binder profile, and were compared with postnatal phenotypes. RESULTS: The Binder phenotype can be detected in early pregnancy (14.5 WG). All foetuses had verticalized nasal bones and midfacial hypoplasia. Punctuate calcifications were found in almost all the cases. No specific maternal auto-antibody has been associated with foetal Binder phenotype. CONCLUSION: Since the Binder phenotype can be diagnosed at ultrasound examination during pregnancy, it is important to establish the underlying cause so as to assess the foetal prognosis. This study stresses the importance of systematic checks for maternal autoimmune disease in cases of prenatally diagnosed Binder phenotypes.

The Renpenning syndrome spectrum: new clinical insights supported by 13 new PQBP1-mutated males.

Since the first reports of polyglutamine-binding protein 1 (PQBP1) mutations in Renpenning syndrome and related disorders, the spectrum of PQBP1-linked clinical manifestations has been outlined from rare published case reports. The phenotypic description is often obtained from medical archives, and therefore, heterogeneous. Moreover, some aspects such as brain imaging or cognitive and behavioral functioning are rarely described. In this study, 13 PQBP1-mutated French patients were subjected to a standardized clinical, cognitive and behavioral assessment. Physical measurements of their relatives were also collected. We report on a recognizable clinical and radiological phenotype. All patients presented with microcephaly, leanness and mild short stature, relative to familial measurements. Three new clinical features are described: upper back progressive muscular atrophy, metacarpophalangeal ankylosis of the thumb and velar dysfunction. The specific facial dysmorphic features included at least four of the following signs: long triangular face, large ridged nose, half-depilated eyebrows, dysplastic or protruding ears and rough slightly sparse hair. An over-aged appearance was noticed in elderly patients. Cortical gyrification was normal based on available magnetic brain imaging of six patients. PQBP1-linked microcephaly (or Renpenning syndrome) is an X-linked mental retardation syndrome, which has clinically recognizable features.

Expanding CEP290 mutational spectrum in ciliopathies.

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Binder phenotype: clinical and etiological heterogeneity of the so-called Binder maxillonasal dysplasia in prenatally diagnosed cases, and review of the literature.

OBJECTIVE: Prenatal Binder profile is a well known clinical phenotype, defined by a flat profile without nasal eminence, contrasting with nasal bones of normal length. Binder profile results of a hypoplasia of the nasal pyramid (sometimes referred to as maxillonasal dysplasia). We report 8 fetuses prenatally diagnosed as Binder phenotype, and discuss their postnatal diagnoses. METHODS: Ultrasonographic detailed measurements in 2D and 3D were done on the 8 fetuses with Binder profile, and were compared with postnatal phenotype. RESULTS: All fetuses have an association of verticalized nasal bones, abnormal convexity of the maxilla, and some degree of chondrodysplasia punctata. The final diagnoses included fetal warfarin syndrome (one patient), infantile sialic acid storage (one patient), probable Keutel syndrome (one patient), and five unclassifiable types of chondrodysplasia punctata. CONCLUSION: This series demonstrates the heterogeneity of prenatally diagnosed Binder phenotype, and the presence of chondrodysplasia punctata in all cases. An anomaly of vitamin K metabolism, possibly due to environmental factors, is suspected in these mild chondrodysplasia punctata. We recommend considering early prophylactic vitamin K supplementation in every suspected acquired vitamin K deficiency including incoercible vomiting of the pregnancy.

Epistatic interactions with a common hypomorphic RET allele in syndromic Hirschsprung disease.

Hirschsprung disease (HSCR) stands as a model for genetic dissection of complex diseases. In this model, a major gene, RET, is involved in most if not all cases of isolated (i.e., nonsyndromic) HSCR, in conjunction with other autosomal susceptibility loci under a multiplicative model. HSCR susceptibility alleles can harbor either heterozygous coding sequence mutations or, more frequently, a polymorphism within intron 1, leading to a hypomorphic RET allele. On the other hand, about 30% of HSCR are syndromic. Hitherto, the disease causing gene has been identified for eight Mendelian syndromes with HSCR: congenital central hypoventilation (CCHS), Mowat-Wilson (MWS), Bardet-Biedl (BBS), Shah-Waardenburg (WS4), cartilage-hair-hypoplasia (CHH), Smith-Lemli-Opitz (SLO), Goldberg-Sprintzsen (GSS), and hydrocephalus due to congenital stenosis of the aqueduct of sylvius (HSAS). According to the HSCR syndrome, the penetrance of HSCR trait varies from 5 to 70%. Trisomy 21 (T21) also predisposes to HSCR. We were able to collect a series of 393 patients affected by CCHS (n = 173), WS4 (n = 24), BBS (n = 51), MWS (n = 71), T21 (n = 46), and mental retardation (MR) with HSCR (n = 28). For each syndrome, we studied the RET locus in two subgroups of patients; i.e., with or without HSCR. We genotyped the RET locus in 393 patients among whom 195 had HSCR, and compared the distribution of alleles and genotypes within the two groups for each syndrome. RET acts as a modifier gene for the HSCR phenotype in patients with CCHS, BBS, and Down syndrome, but not in patients with MWS and WS4. The frequent, low penetrant, predisposing allele of the RET gene can be regarded as a risk factor for the HSCR phenotype in CCHS, BBS, and Down syndrome, while its role is not significant in MWS and WS4. These data highlight the pivotal role of the RET gene in both isolated and syndromic HSCR.

Is the CAG repeat of mitochondrial DNA polymerase gamma (POLG) associated with male infertility? A multi-centre French study.

BACKGROUND: Recent data emphasized the implication of polymerase gamma (POLG) CAG repeats in infertility, making it a very attractive gene for study. A comparison of POLG CAG repeats in infertile and fertile men showed a clear association between the absence of the usual 10-CAG allele and male infertility, excluding azoospermia. It has also been suggested that the POLG gene polymorphism should be considered as a possible contributing factor in unexplained couple infertility where semen parameters are normal. In this study, we investigated the POLG CAG repeats, in a well-defined population of patients with severe male factor infertility. METHODS: We conducted a large study of POLG CAG repeats in 433 infertile and 91 fertile, normozoospermic and healthy males. In all subjects, phenotypic data, including semen parameters, hormonal status and clinical profiles, were available. RESULTS: Thirteen 'homozygous mutants' (3%) were found among the 433 idiopathic infertile patients. The follow-up of the 13 'homozygous mutant' resulted in pregnancy for more than half of the couples, through assisted reproductive techniques or even spontaneously. In addition, one 'homozygous mutant' was identified in 91 fertile men (1.1%) CONCLUSION: Under our conditions, our study does not confirm any relationship between the polymorphic CAG repeat in the POLG gene and male infertility.

[A simple, low-cost and non-invasive method for screening Y microdeletions in infertile men]. / Evaluation d'une technique simple et rapide de détection de microdélétions du bras long du chromosome Y.

OBJECTIVES: Recent investigations showed a high prevalence of Y chromosome microdeletions in men with severely impaired spermatogenesis. Screening for these men is recommended prior to assisted reproduction techniques. The aim of this study was to set up a simple method to detect Y deletion in infertile men. First, we tested the feasibility of cytobrush to collect oral cells as source of DNA. Second, we compared a classic PCR corresponding to European recommendations to the Promega kit. PATIENTS AND METHODS: Seventeen infertile male patients with previously characterized deletions were included in the present study, after fully informed written consent. Both oral cells and blood were used for DNA extraction. A specific DNA extraction protocol was carried out on the buccal cells. The DNAs were tested for Y deletion screening by two different methods. RESULTS: We retrieved between 4 and 10 microg of DNA per brush from buccal cells, allowing several multiplex PCR. The Promega kit detected all the deletions but one: an AZFa deletion was not detected by the two markers of the kit covering this region. In addition, sY130, sY133 and SY153, included in the kit, are not reliable. DISCUSSION AND CONCLUSIONS: Buccal cells represent a convenient substitute for blood in testing for Y microdeletions. Both false negative and false positive results were obtained with Promega Kit. On the opposite, PCR according to the European recommendations allow the accurate detection of Y microdeletion in our 17 cases, at a lower cost.