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While the XYY and XXYY syndromes have been several time described in patients, the combination of both syndromes in an individual is a rare event and may result in a severe phenotype. In the present observation, a boy with congenital scoliosis due to segmented thoracic hemivertebra associated with radioulnar synostosis and congenital heart disease is described. Chromosome G-banding and FISH analysis demonstrated a de novo mosaic karyotype 48, XXYY/47, XYY in this patient. To the best of our knowledge, this is the first report of a combination of XYY and XXYY syndromes.

Autophagy is a cellular process through which toxic aggregates, pathogens, and damaged organelles are disposed of and essential metabolites recycled. This study challenges the belief that a core autophagy protein is indispensable.

The skeletal ciliopathies are a heterogeneous group of disorders with a significant clinical and genetic variability and the main clinical features are thoracic hypoplasia and short tubular bones. To date, 25 genes have been identified in association with skeletal ciliopathies. Mutations in the KIAA0753 gene have recently been associated with Joubert syndrome (JBTS) and orofaciodigital (OFD) syndrome. We report biallelic pathogenic variants in KIAA0753 in four patients with short-rib type skeletal dysplasia. The manifestations in our patients are variable and ranging from fetal lethal to viable and moderate skeletal dysplasia with narrow thorax and abnormal metaphyses. We demonstrate that KIAA0753 is expressed in normal fetal human growth plate and show that the affected fetus, with a compound heterozygous frameshift and a nonsense mutation in KIAA0753 , has an abnormal proliferative zone and a broad hypertrophic zone. The importance of KIAA0753 for normal skeletal development is further confirmed by our findings that zebrafish embryos homozygous for a nonsense mutation in kiaa0753 display altered cartilage patterning.

Background Stuve-Wiedemann syndrome (SWS) is a rare and severe genetic disease characterized by skeletal anomalies and dysautonomic disturbances requiring appropriate care. Peer support is mandatory to fill the lack of clinical recommendations in such rare diseases. We report a new case and provide the first systematic review of all previous published cases. Objective To better describe the timeline of SWS and to improve paediatric management. Data sources SWS English publications available on Pubmed until 31/03/2021. Study selection Case description combining typical osteo-articular and dysautonomic involvement (with 2 items by categories required for children < 2 years and 3 items > 2 years). Data extraction Demographic, clinical, genetics and outcome data. Results In our cohort of 69 patients, the median age at report was 32 months. Only 46% presented antenatal signs. Mortality rate is higher during the first 2 years (42% < 2 years; 10% > 2 years) mainly due to respiratory failure, pulmonary arterial hypertension appearing to be a poor prognosis factor (mortality rate 63%). After 2 years, orthopaedic symptoms significantly increase including joint mobility restriction (81%), spinal deformations (77%) and fractures (61%). Conclusions Natural history of SWS is marked by a high mortality rate before 2 years due to dysautonomic disturbances. A specialized multidisciplinary approach is needed to address these early mortality risks and then adapt to the specific, mainly orthopaedic, needs of patients after 2 years of age. Further research is required to provide clinical guidelines and improve pre-natal counselling.

Genetic variants in the zone of polarizing activity regulatory sequence (ZRS) that induce ectopic expression of the SHH gene have been associated with different ZRS-related phenotypes. We report the first patient with a de novo variant, c.423+4916 T>C, in ZRS (previously classified as a variant of uncertain significance) that causes tibial hemimelia-polysyndactyly-triphalangeal thumb syndrome (THPTTS). A two-month-old male patient presented with bilateral preaxial polydactyly, triphalangeal thumb, and tibial agenesis and was heterozygous for the variant c.423+4916T>C (neither of his parents was a carrier). The findings obtained from the family study were sufficient to reclassify the variant from “uncertain significance” to “likely pathogenic” according to three criteria from the American College of Medical Genetics and Genomics guidelines, as follows: (1) absence of gnomAD, (2) confirmation of paternity and maternity, and (3) strong phenotype–genotype association. In ZRS-associated syndromes, a wide clinical spectrum has been observed, ranging from polydactyly to THPTTS; our patient has the most severe and rare phenotype. We did not perform functional assays. However, the c.423+4916T>C variant is flanked by three variants, which have been proven not only to cause the phenotype but also to increase the expression of SHH. Through all this data gathering, we consider the c.423+4916T>C variant to be causative of THPTTS.

Heinz Jungbluth and colleagues report the identification of mutations in EPG5 that cause Vici syndrome, characterized by callosal agenesis, cataracts, cardiomyopathy, combined immunodeficiency and hypopigmentation. EPG5 encodes a regulator of autophagy, and the identified mutations cause defective autophagosomal function. Vici syndrome is a recessively inherited multisystem disorder characterized by callosal agenesis, cataracts, cardiomyopathy, combined immunodeficiency and hypopigmentation. To investigate the molecular basis of Vici syndrome, we carried out exome and Sanger sequence analysis in a cohort of 18 affected individuals. We identified recessive mutations in EPG5 (previously KIAA1632 ), indicating a causative role in Vici syndrome. EPG5 is the human homolog of the metazoan-specific autophagy gene epg-5 , encoding a key autophagy regulator (ectopic P-granules autophagy protein 5) implicated in the formation of autolysosomes. Further studies showed a severe block in autophagosomal clearance in muscle and fibroblasts from individuals with mutant EPG5 , resulting in the accumulation of autophagic cargo in autophagosomes. These findings position Vici syndrome as a paradigm of human multisystem disorders associated with defective autophagy and suggest a fundamental role of the autophagy pathway in the immune system and the anatomical and functional formation of organs such as the brain and heart.

Dysmorphology syndromes are among the most common referrals to clinical genetics specialists. Inability to match the dysmorphology pattern to a known syndrome can pose a major diagnostic challenge. With an aim to accelerate the establishment of new syndromes and their genetic etiology, we describe our experience with multiplex consanguineous families that appeared to represent novel autosomal recessive dysmorphology syndromes at the time of evaluation. Combined autozygome/exome analysis of multiplex consanguineous families with apparently novel dysmorphology syndromes. Consistent with the apparent novelty of the phenotypes, our analysis revealed a strong candidate variant in genes that were novel at the time of the analysis in the majority of cases, and 10 of these genes are published here for the first time as novel candidates (CDK9, NEK9, ZNF668, TTC28, MBL2, CADPS, CACNA1H, HYAL2, CTU2, and C3ORF17). A significant minority of the phenotypes (6/31, 19%), however, were caused by genes known to cause Mendelian phenotypes, thus expanding the phenotypic spectrum of the diseases linked to these genes. The conspicuous inheritance pattern and the highly specific phenotypes appear to have contributed to the high yield (90%) of plausible molecular diagnoses in our study cohort. Reporting detailed clinical and genomic analysis of a large series of apparently novel dysmorphology syndromes will likely lead to a trend to accelerate the establishment of novel syndromes and their underlying genes through open exchange of data for the benefit of patients, their families, health-care providers, and the research community.

Myogenic fusion, primarily regulated by the Myomaker and Myomixer proteins, is essential for skeletal muscle development, yet its mechanisms remain poorly understood. This study presents the clinical and molecular details of the third and fourth reported patients with biallelic variants in MYMX , the gene that encodes Myomixer. We identified a homozygous truncating variant [c.107 T > A (p.Leu36Ter)] and a homozygous stop-codon loss variant [c.255 A > G (p.Ter85TrpextTer41)] in MYMX , both associated with a complex neuromuscular syndrome characterized by generalized hypotonia, congenital myopathy, facial nerve palsy, growth restriction and facial dysmorphism. Additional variable features include hearing loss (confirmed in one patient, suspected in the other), scoliosis, joint contractures, cleft palate, hypoglossia, potentially contributing to Pierre Robin sequence, and abnormalities on neuroimaging studies including cerebellar atrophy and Chiari 1 deformity. Comparative analysis of patients with pathogenic variants in MYMK and MYMX , including our cases, reveals largely overlapping phenotypes, underscoring their synergistic role in myofiber formation and implicating their involvement in the etiology of neuromuscular conditions.

Endocrine-cerebro-osteodysplasia (ECO) syndrome is a recessive genetic disorder associated with multiple congenital defects in endocrine, cerebral, and skeletal systems that is caused by a missense mutation in the mitogen-activated protein kinase-like intestinal cell kinase (ICK) gene. In algae and invertebrates, ICK homologs are involved in flagellar formation and ciliogenesis, respectively. However, it is not clear whether this role of ICK is conserved in mammals and how a lack of functional ICK results in the characteristic phenotypes of human ECO syndrome. Here, we generated Ick knockout mice to elucidate the precise role of ICK in mammalian development and to examine the pathological mechanisms of ECO syndrome. Ick null mouse embryos displayed cleft palate, hydrocephalus, polydactyly, and delayed skeletal development, closely resembling ECO syndrome phenotypes. In cultured cells, down-regulation of Ick or overexpression of kinase-dead or ECO syndrome mutant ICK resulted in an elongation of primary cilia and abnormal Sonic hedgehog (Shh) signaling. Wild-type ICK proteins were generally localized in the proximal region of cilia near the basal bodies, whereas kinase-dead ICK mutant proteins accumulated in the distal part of bulged ciliary tips. Consistent with these observations in cultured cells, Ick knockout mouse embryos displayed elongated cilia and reduced Shh signaling during limb digit patterning. Taken together, these results indicate that ICK plays a crucial role in controlling ciliary length and that ciliary defects caused by a lack of functional ICK leads to abnormal Shh signaling, resulting in congenital disorders such as ECO syndrome.

Existed classifications of congenital proximal radioulnar synostosis (PRUS) mainly focus on osseous changes and do not cover all types of congenital PRUS, ignoring the role and developing status of the supinator. This study aims to explore the correlation between supinator development and radiographic deformity of congenital PRUS. Pediatric patients diagnosed with congenital PRUS in two pediatric Orthopedic centers were evaluated retrospectively. MRI and radiographic images of their bilateral forearms (including normal ones) were collected. The area of supinator, extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), brachioradialis (BRAR) muscle and extensor indicis (EI) muscle were measured on each forearm. The ratios of these muscles were calculated and regarded as an indicator of the developing status of supinator muscle. Twenty-seven congenital PRUS forearms of 16 patients (average 3.45 years) were included. A new MRI & X-ray classification system was proposed to cover all types of radiographic deformity and provide a comprehensive description of supinator development. This study revealed the relation between MRI measured supinator volume and radiographic deformity of congenital PRUS. Supinator muscles were observed in all congenital PRUS cases. A novel classification was proposed, providing a more comprehensive understanding of congenital PRUS.