New description of an MRPS2 homozygous patient: Further features to help expend the phenotype.

Mutated mito-ribosomal protein S2 (MRPS2) was already described in only three subjects, two with sensorineural hearing impairment, mild developmental delay, hypoglycemia, lactic acidemia and combined oxidative phosphorylation system deficiency and another, recently, presenting with a less severe phenotype. In order to expand the phenotype, we describe a new MRPS2 homozygous subject who shows particular features which have not yet been reported: initial microcephaly, joint hypermobility and autistic features.

Oral Phenotype of Singleton-Merten Syndrome: A Systematic Review Illustrated With a Case Report.

Background: Singleton-Merten syndrome type 1 (SGMRT1) is a rare autosomal dominant disorder caused by IFIH1 variations with blood vessel calcifications, teeth anomalies, and bone defects. Aim: We aimed to summarize the oral findings in SGMRT1 through a systematic review of the literature and to describe the phenotype of a 10-year-old patient with SGMRT1 diagnosis. Results: A total of 20 patients were described in the literature, in nine articles. Eight IFIH1 mutations were described in 11 families. Delayed eruption, short roots, and premature loss of permanent teeth were the most described features (100%). Impacted teeth (89%) and carious lesions (67%) were also described. Our patient, a 10-year-old male with Singleton-Merten syndrome, presented numerous carious lesions, severe teeth malposition, especially in the anterior arch, and an oral hygiene deficiency with a 100% plaque index. The panoramic X-ray did not show any dental agenesis but revealed very short roots and a decrease in the jaw alveolar bone height. The whole-genome sequencing analysis revealed a heterozygous de novo variant in IFIH1 (NM_022168.4) c.2465G > A (p.Arg822Gln). Conclusion: Confused descriptions of oral features occurred in the literature between congenital findings and "acquired" pathology, especially carious lesions. The dental phenotype of these patients encompasses eruption anomalies (delayed eruption and impacted teeth) and lack of root edification, leading to premature loss of permanent teeth, and it may contribute to the diagnosis. An early diagnosis is essential to prevent teeth loss and to improve the quality of life of these patients. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], identifier [CRD42022300025].

Autosomal Recessive Cerebellar Atrophy and Spastic Ataxia in Patients With Pathogenic Biallelic Variants in GEMIN5.

The hereditary ataxias are a heterogenous group of disorders with an increasing number of causative genes being described. Due to the clinical and genetic heterogeneity seen in these conditions, the majority of such individuals endure a diagnostic odyssey or remain undiagnosed. Defining the molecular etiology can bring insights into the responsible molecular pathways and eventually the identification of therapeutic targets. Here, we describe the identification of biallelic variants in the GEMIN5 gene among seven unrelated families with nine affected individuals presenting with spastic ataxia and cerebellar atrophy. GEMIN5, an RNA-binding protein, has been shown to regulate transcription and translation machinery. GEMIN5 is a component of small nuclear ribonucleoprotein (snRNP) complexes and helps in the assembly of the spliceosome complexes. We found that biallelic GEMIN5 variants cause structural abnormalities in the encoded protein and reduce expression of snRNP complex proteins in patient cells compared with unaffected controls. Finally, knocking out endogenous Gemin5 in mice caused early embryonic lethality, suggesting that Gemin5 expression is crucial for normal development. Our work further expands on the phenotypic spectrum associated with GEMIN5-related disease and implicates the role of GEMIN5 among patients with spastic ataxia, cerebellar atrophy, and motor predominant developmental delay.