A severe case of Frank-ter Haar syndrome and literature review: Further delineation of the phenotypical spectrum.

Frank-ter Haar syndrome (FTHS) is a rare autosomal recessive syndrome resulting from mutations in the SH3PXD2B gene involved in the formation of podosomes and invadopodia which have a role in extracellular matrix remodelling and cell migration. FTHS is characterized by facial dysmorphism, megalocornea, inconstant glaucoma, variable developmental delay, skeletal and cardiac anomalies. To date, 40 patients have been reported in the literature with a clinical diagnosis of FTHS, only 20 patients having identified mutations. We present a review of these 20 reported patients and describe a patient born to non-consanguineous parents, with intrauterine growth retardation, hypotonia, congenital glaucoma, caudal appendix, scoliosis, camptodactyly, ventricular septal defect, thin corpus callosum and craniofacial features suggestive of FTHS. Clinical evolution resulted in buphthalmos worsening, coarsening of the facial features and respiratory failure leading to death at 4,5 months. Diagnosis was confirmed by the identification of a previously known homozygous mutation c.969delG, p.(Arg324Glyfs*19) in SH3PXD2B. This is the first description of very severe phenotype with lethal respiratory impairment in FTHS. Since very few patients are described in the literature, and 2 out of the 3 patients carrying the c.969delG mutation had a favourable clinical course, more cases are needed to better characterize the phenotype and understand the natural history of this syndrome. Furthermore, we hypothesize that the alteration of podosomes function could lead to a reduction of the extracellular matrix degradation and accumulation of the latter in the extracellular space, which might explain the coarsening of the facial features and the severe refractory glaucoma.

Uncommon nucleotide excision repair phenotypes revealed by targeted high-throughput sequencing.

BACKGROUND: Deficient nucleotide excision repair (NER) activity causes a variety of autosomal recessive diseases including xeroderma pigmentosum (XP) a disorder which pre-disposes to skin cancer, and the severe multisystem condition known as Cockayne syndrome (CS). In view of the clinical overlap between NER-related disorders, as well as the existence of multiple phenotypes and the numerous genes involved, we developed a new diagnostic approach based on the enrichment of 16 NER-related genes by multiplex amplification coupled with next-generation sequencing (NGS). METHODS: Our test cohort consisted of 11 DNA samples, all with known mutations and/or non pathogenic SNPs in two of the tested genes. We then used the same technique to analyse samples from a prospective cohort of 40 patients. Multiplex amplification and sequencing were performed using AmpliSeq protocol on the Ion Torrent PGM (Life Technologies). RESULTS: We identified causative mutations in 17 out of the 40 patients (43%). Four patients showed biallelic mutations in the ERCC6(CSB) gene, five in the ERCC8(CSA) gene: most of them had classical CS features but some had very mild and incomplete phenotypes. A small cohort of 4 unrelated classic XP patients from the Basque country (Northern Spain) revealed a common splicing mutation in POLH (XP-variant), demonstrating a new founder effect in this population. Interestingly, our results also found ERCC2(XPD), ERCC3(XPB) or ERCC5(XPG) mutations in two cases of UV-sensitive syndrome and in two cases with mixed XP/CS phenotypes. CONCLUSIONS: Our study confirms that NGS is an efficient technique for the analysis of NER-related disorders on a molecular level. It is particularly useful for phenotypes with combined features or unusually mild symptoms. Targeted NGS used in conjunction with DNA repair functional tests and precise clinical evaluation permits rapid and cost-effective diagnosis in patients with NER-defects.

Phenotypic variability in ARCA2 and identification of a core ataxic phenotype with slow progression.

Autosomal recessive cerebellar ataxia 2 (ARCA2) is a recently identified recessive ataxia due to ubiquinone deficiency and biallelic mutations in the ADCK3 gene. The phenotype of the twenty-one patients reported worldwide varies greatly. Thus, it is difficult to decide which ataxic patients are good candidates for ADCK3 screening without evidence of ubiquinone deficiency. We report here the clinical and molecular data of 10 newly diagnosed patients from seven families and update the disease history of four additional patients reported in previous articles to delineate the clinical spectrum of ARCA2 phenotype and to provide a guide to the molecular diagnosis. First signs occurred before adulthood in all 14 patients. Cerebellar atrophy appeared in all instances. The progressivity and severity of ataxia varied greatly, but no patients had the typical inexorable ataxic course that characterizes other childhood-onset recessive ataxias. The ataxia was frequently associated with other neurological signs. Importantly, stroke-like episodes contributed to significant deterioration of the neurological status in two patients. Ubidecarenone therapy markedly improved the movement disorders, including ataxia, in two other patients. The 7 novel ADCK3 mutations found in the 10 new patients were two missense and five truncating mutations. There was no apparent correlation between the genotype and the phenotype. Our series reveals that the clinical spectrum of ARCA2 encompasses a range of ataxic phenotypes. On one end, it may manifest as a pure ataxia with very slow progressivity and, on the other end, as a severe infantile encephalopathy with cerebellar atrophy. The phenotype of most patients, however, lies in between. It is characterized by a very slowly progressive or apparently stable ataxia associated with other signs of central nervous system involvement. We suggest undergoing the molecular analysis of ADCK3 in patients with this phenotype and in those with cerebellar atrophy and a stroke-like episode. The diagnosis of patients with a severe ARCA2 phenotype may also be performed on the basis of biological data, i.e. low ubiquinone level or functional evidence of ubiquinone deficiency. This diagnosis is crucial since the neurological status of some patients may be improved by ubiquinone therapy.

Family beyond parents? An exploration of family configurations and psychological adjustment in young adults with intellectual disabilities.

This research explores the family configurations of young adults with intellectual disability. Based on a sample of 40 individuals interviewed two times in a year, we found as many as four types of family configurations, with distinct compositions, and different types of social capital. This diversity is not without consequences for individual psychological adjustment. The results are discussed in the light of the configurational approach to families.