Foveal hypoplasia in parents of patients with albinism.

BACKGROUND: Albinism is a group of genetic disorders characterized by general skin and retinal hypopigmentation. It is in most cases an autosomal recessive condition. Foveal hypoplasia (FH) is one of the main criteria for the diagnosis of albinism. The aim of this study was to analyze the macular profile of the parents of patients with albinism. METHODS: This study included a case series of 27 patients with albinism seen in Rothschild Foundation between April 2017 and February 2020. Spectral-domain optical coherence tomography (SD-OCT) and OCT angiography (OCT-A) were performed in every patient when possible and in every available parents. FH was graded according to Thomas' classification based on OCT. Next generation sequencing-based gene panel testing was performed in parents and children when a FH was detected on OCT in a parent. RESULTS: Twenty-seven patients with albinism were examined. Nine parents had FH based on the OCT B-scan (33%). In parents without FH based on the SD-OCT B-scan (67%), OCT-A showed a reduced avascular zone in the deep vascular plexus in 4 parents. Six parents carried variants that could explain their phenotype, including TYR R402Q hypomorphic alleles. CONCLUSION: This study showed the presence of FH in parents of patients with albinism, and aimed to genetically explain this phenotype.

Management of albinism: French guidelines for diagnosis and care.

Albinism is a worldwide genetic disorder caused by mutations in at least 20 genes, identified to date, that affect melanin production or transport in the skin, hair and eyes. Patients present with variable degrees of diffuse muco-cutaneous and adnexal hypopigmentation, as well as ocular features including nystagmus, misrouting of optic nerves and foveal hypoplasia. Less often, albinism is associated with blood, immunological, pulmonary, digestive and/or neurological anomalies. Clinical and molecular characterizations are essential in preventing potential complications. Disease-causing mutations remain unknown for about 25% of patients with albinism. These guidelines have been developed for the diagnosis and management of syndromic and non-syndromic forms of albinism, based on a systematic review of the scientific literature. These guidelines comprise clinical and molecular characterization, diagnosis, therapeutic approach and management.

Further delineation of the phenotype caused by biallelic variants in the WDR4 gene.

Microcephalic primordial dwarfisms are a group of rare Mendelian disorders characterized by severe growth retardation and microcephaly. The molecular basis is heterogeneous, with disease-causing genes implicated in different cellular functions. Recently, 2 patients were reported with the same homozygous variant in the WDR4 gene, coding for an enzyme responsible for the m7 G46 post transcriptional modification of tRNA. We report here 2 sisters harboring compound heterozygous variants of WDR4. Their phenotype differs from that of the first 2 described patients: they both have a severe microcephaly but only one of the 2 sisters had a head circumference at birth below -2 SD, their intellectual deficiency is less severe, and they have a growth hormone deficiency and a partial hypogonadotropic hypogonadotropism. One of the 2 variants is a frameshift mutation, and the other one is a missense occurring in the same nucleotide affected by the first reported pathogenic variant, which could therefore be a mutational hot spot. The description of these 2 sisters allow us to confirm that biallelic variants in the WDR4 gene can lead to a specific phenotype, characterized by severe growth retardation and microcephaly.

Fetal phenotypes in otopalatodigital spectrum disorders.

Otopalatodigital spectrum disorders (OPDSD) include OPD syndromes types 1 and type 2 (OPD1, OPD2), Melnick-Needles syndrome (MNS), and frontometaphyseal dysplasia (FMD). These conditions are clinically characterized by variable skeletal dysplasia associated in males, with extra-skeletal features including brain malformations, cleft palate, cardiac anomalies, omphalocele and obstructive uropathy. Mutations in the FLNA gene have been reported in most FMD and OPD2 cases and in all instances of typical OPD1 and MNS. Here, we report a series of 10 fetuses and a neonatally deceased newborn displaying a multiple congenital anomalies syndrome suggestive of OPDSD and in whom we performed FLNA analysis. We found a global mutation rate of 44%. This series allows expanding the clinical and FLNA mutational spectrum in OPDSD. However, we emphasize difficulties to correctly discriminate OPDSD based on clinical criteria in fetuses due to the major overlap between these conditions. Molecular analyses may help pathologists to refine clinical diagnosis according to the type and the location of FLNA mutations. Discriminating the type of OPDSD is of importance in order to improve the genetic counseling to provide to families.

Homozygous 16p13.11 duplication associated with mild intellectual disability and urinary tract malformations in two siblings born from consanguineous parents.

The use of array-comparative genomic hybridization (array-CGH) in routine clinical work has allowed the identification of many new copy number variations (CNV). The 16p13.11 duplication has been implicated in various congenital anomalies and neurodevelopmental disorders, but it has also been identified in healthy individuals. We report a clinical observation of two brothers from related parents each carrying a homozygous 16p13.11 duplication. The propositus had mild intellectual disability and posterior urethral valves with chronic renal disease. His brother was considered a healthy child with only learning disabilities and poor academic performances. However, a routine medical examination at 25-years-old revealed a mild chronic renal disease and ureteropelvic junction obstruction. Furthermore, the father presented with a unilateral renal agenesis, thus it seemed that a "congenital anomalies of kidney and urinary tract" (CAKUT) phenotype segregated in this family. This may be related to the duplication, but we cannot exclude the involvement of additional genetic or non-genetic factors in the urological phenotype. Several cohort studies showed association between this chromosomal imbalance and different clinical manifestations, but rarely with CAKUT. The duplication reported here was similar to the larger one of 3.4 Mb previously described versus the more common of 1.6 Mb. It encompassed at least 11 known genes, including the five ohnologs previously identified. Our observation, in addition to expanding the clinical spectrum of the duplication provides further support to understanding the underlying pathogenic mechanism.

Blepharophimosis, ptosis, epicanthus inversus syndrome with translocation and deletion at chromosome 3q23 in a black African female.

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disorder whose main features are the abnormal shape, position and alignment of the eyelids. Type I refers to BPES with female infertility from premature ovarian failure while type II is limited to the ocular features. A causative gene, FOXL2, has been localized to 3q23. We report a black female who carried a de novo chromosomal translocation and 3.13 Mb deletion at 3q23, 1.2 Mb 5' to FOXL2. This suggests the presence of distant cis regulatory elements at the extended FOXL2 locus. In spite of 21 protein coding genes in the 3.13 Mb deleted segment, the patient had no other malformation and a strictly normal psychomotor development at age 2.5 years. Our observation confirms panethnicity of BPES and adds to the knowledge of the complex cis regulation of human FOXL2 gene expression.

[Polymorphic expression of epilepsy and cognitive impairment in ring chromosome 20 syndrome]. / Polymorphisme d'expression de l'atteinte épileptique et cognitive du syndrome du chromosome 20 en anneau.

Ring chromosome 20 syndrome combines epilepsy with varying levels of mental retardation, behavioral disorders, and malformations. Epilepsy is generally serious, with frequent drug resistance. The pathophysiology of seizures remains unclear. Rearrangements of two epilepsy genes, CHRNA4 and KCNQ2, have been raised as the cause. We report the observation of one child, with a telomeric deletion 20p13, with no epileptic symptoms. Preservation of CHRNA4 and KCNQ2 gene activity could explain this distinctive feature.

Bilateral periventricular nodular heterotopia in France: frequency of mutations in FLNA, phenotypic heterogeneity and spectrum of mutations.

Bilateral periventricular nodular heterotopia (BPNH) is the most common form of periventricular heterotopia. Mutations in FLNA, encoding filamin A, are responsible for the X linked dominant form of BPNH (FLNA-BPNH). Recently, atypical phenotypes including BPNH with Ehlers-Danlos syndrome (BPNH-EDS) have been recognised. A total of 44 FLNA mutations have so far been reported in this phenotype. Most of these mutations lead to a truncated protein, but few missense mutations have also been described. Here, the results of a mutation screening conducted in a series of 32 BPNH patients with the identification of 12 novel point mutations in 15 patients are reported. Nine mutations were truncating, while three were missense. Three additional patients with BPNH-EDS and a mutation in FLNA are described. No phenotype-genotype correlations could be established, but these clinical data sustain the importance of cardiovascular monitoring in FLNA-BPNH patients.

Tumoral calcinosis due to GALNT3 C.516-2A >T mutation in a black African family.

Familial Tumoral Calcinosis (FTC) is a rare autosomal recessive disorder of the phosphocalcic metabolism caused by mutations in the FGF23 or GALNT3 genes. We have identified a Beninese family in which two brothers present FTC caused by a homozygous A>T transversion at the acceptor splice site in intron 1 of GALNT3 gene. We report on the clinical, biochemical, histopathological and molecular spectrum of the disorder in this family. The particularly severe phenotype, the amelogenesis imperfecta, and the carbapatite deposit observed in these patients, seem to be characteristic of our observations.

Influence of FCGR3A-V212F and TNFRSF1B-M196R genotypes in patients with rheumatoid arthritis treated with infliximab therapy.

OBJECTIVE: Anti-TNF-alpha therapies are widely used in rheumatoid arthritis (RA) patients. Despite their clearly proven efficacy, some discrepancies were observed in the treatment response with 40% of non-responder patients. The aim of this study is to determine whether two functional single-nucleotide polymorphisms, V212F in the FCGR3A, and M196R in the TNFRSF1B genes correlate with rheumatoid arthritis susceptibility and response to anti-TNF-alpha therapy. METHODS: The population study was composed of a French cohort of 78 RA patients and 70 healthy controls. Allele and genotype frequencies were compared between patients and controls, according to their response to infliximab therapy, using the American College of Rheumatology (ACR) response criteria. RESULTS: No association was found between these two SNPs and RA susceptibility. A significant correlation was found between 196R allele carriers and low response to infliximab therapy. CONCLUSION: This is the first report of a statistically significant association between the TNFRSF1B-M196R SNP and response to infliximab in a French cohort. Larger studies are needed to confirm the relevance of this association.

Bardet-biedl syndrome and brain abnormalities.

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder with clinical and genetic heterogeneity. The main features are obesity, polydactyly, pigmentary retinopathy, learning disabilities, hypogonadism, and renal abnormalities. To date, eleven genes have been cloned but there is still little knowledge about genotype/phenotype correlations. We describe three additional cases with BBS and cerebral abnormalities and focus on cerebellar abnormalities in BBS.

Oro-dental features as useful diagnostic tool in Rubinstein-Taybi syndrome.

Rubinstein-Taybi syndrome (RTS; OMIM # 180849) is a well-known disorder characterized by mental and growth retardation, broad thumbs and great toes, and unusual facial characteristics. We studied oro-dental findings in a group of RTS patients: 12 from the UK, 2 from Greece, and 26 from France. All were examined by two investigators, using the Diagnosing Dental Defects Database record form to document these. Various oro-dental features were found: small mouth, retrognathia, micrognathia, highly arched and narrow palate, talon cusps, expressed crowding, screwdriver incisors, cross bites, and enamel hypoplasia. Eruption was usually normal. Specific attention for these anomalies should facilitate diagnosis and help adequate management.

Analysis of the effect of aluminum in drinking water and transferrin C2 allele on Alzheimer's disease.

Although highly controversial, the hypothesis of a link between aluminum (Al) in drinking water and Alzheimer's disease (AD) has been supported by several epidemiological studies. Transferrin (Tf) is a major transport protein for both iron and Al. Moreover, it has been demonstrated that defective binding of iron and Al to the Tf variant C2 could be present in AD. Individuals carrying the Tf C2 allele might therefore be at greater risk of developing AD. We investigated whether the Tf C2 allele might be responsible for susceptibility to AD in a sample of 292 subjects (with 55 AD) aged > or = 75 years from south-west France, some exposed to high levels of Al in tap water (n = 181 subjects) and others to low levels of Al (n = 111 subjects). We also examined the combined genetic effects of Tf C2 and epsilon4 allele of apolipoprotein E gene (ApoE). Logistic regression analysis showed that neither Tf C2 nor its interaction with Al or with the epsilon4 allele of the ApoE were significantly associated with the risk of AD.

Mosaic maternal uniparental isodisomy for chromosome 7q21-qter.

Uniparental disomy (UPD) for several human chromosomes is associated with clinical abnormalities. We report the case of a 2-year-old boy with severe intrauterine and post-natal growth retardation (IUGR/PNGR) and highly variable sweat chloride concentrations. The patient was identified as heterozygous for the F508del mutation of the CFTR (cystic fibrosis transmembrane conductance regulator) gene. Unexpectedly, the signal corresponding to the maternally inherited F508del allele appeared much more intense than the paternally derived wild allele. Molecular analysis including polymorphic marker studies, microsatellites and single-nucleotide polymorphisms subsequently showed that the boy was a carrier of a de novo mosaic maternal isodisomy of a chromosome 7 segment while there was a biparental inheritance of the rest of the chromosome. This is the first report of a mosaic partial UPD7. The matUPD7 segment at 7q21-qter extends for 72.7 Mb. The karyotype (550 bands) of our patient was normal, and fluorescence in situ hybridization with probes mapping around the CFTR gene allowed us to rule out a partial duplication. The detection of this chromosomal rearrangement confirms the hypothesis that the 7q31-qter segment is a candidate for the localization of human imprinted genes involved in the control of IUGR and PNGR. It also emphasizes the importance of searching for UPD7 in severe, isolated and unexplained IUGR and PNGR.

Genotype-phenotype correlation in Costello syndrome: HRAS mutation analysis in 43 cases.

BACKGROUND: Costello syndrome (CS) is a rare multiple congenital abnormality syndrome, associated with failure to thrive and developmental delay. One of the more distinctive features in childhood is the development of facial warts, often nasolabial and in other moist body surfaces. Individuals with CS have an increased risk of malignancy, suggested to be about 17%. Recently, mutations in the HRAS gene on chromosome 11p13.3 have been found to cause CS. METHODS: We report here the results of HRAS analysis in 43 individuals with a clinical diagnosis of CS. RESULTS: Mutations were found in 37 (86%) of patients. Analysis of parental DNA samples was possible in 16 cases for both parents and in three cases for one parent, and confirmed the mutations as de novo in all of these cases. Three novel mutations (G12C, G12E, and K117R) were found in five cases. CONCLUSIONS: These results confirm that CS is caused, in most cases, by heterozygous missense mutations in the proto-oncogene HRAS. Analysis of the major phenotypic features by mutation suggests a potential correlation between malignancy risk and genotype, which is highest for patients with an uncommon (G12A) substitution. These results confirm that mutation testing for HRAS is a reliable diagnostic test for CS.

[Costello syndrome: clinical aspects and tumor risk]. / Syndrome de Costello: aspects cliniques et risque tumoral.

Costello syndrome is a sporadic development anomaly suggesting a genetic determinism. Main features include characteristic facial features, mental retardation, growth retardation, cutis laxa, heart malformation, and peri-orificial papillomata. In previous reported cases, the frequency of tumors is 15%, which argues for a screening protocol. The occurrence of a tumor in a child with growth retardation and cutis laxa must be reminiscent of Costello syndrome. The determinism of this syndrome is still unknown, and the hypothesis of an inactivation of a tumor suppressor gene is to be considered.