Genome sequencing identifies biallelic variants in SCLT1 in a patient with syndromic nephronophthisis: Reflections on the SCLT1-related ciliopathy spectrum.

Ciliopathies represent a major category of rare multisystem disease. Arriving at a specific diagnosis for a given patient is challenged by the significant genetic and clinical heterogeneity of these conditions. We report the outcome of the diagnostic odyssey of a child with obesity, renal, and retinal disease. Genome sequencing identified biallelic splice site variants in sodium channel and clathrin linker 1 (SCLT1), an emerging ciliopathy gene. We review the literature on all patients reported with biallelic SCLT1 variants highlighting a frequent clinical presentation that overlaps Bardet-Biedl and Senior-Loken syndromes. We also discuss current concepts in syndrome designation in light of these data.

Wolfram Syndrome: A Case Report and Review of Clinical Manifestations, Genetics Pathophysiology, and Potential Therapies.

BACKGROUND: Classical Wolfram syndrome (WS) is a rare autosomal recessive disorder caused by mutations in WFS1, a gene implicated in endoplasmic reticulum (ER) and mitochondrial function. WS is characterized by insulin-requiring diabetes mellitus and optic atrophy. A constellation of other features contributes to the acronym DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness). This review seeks to raise awareness of this rare form of diabetes so that individuals with WS are identified and provided with appropriate care. CASE: We describe a woman without risk factors for gestational or type 2 diabetes who presented with gestational diabetes (GDM) at the age of 39 years during her first and only pregnancy. Although she had optic atrophy since the age of 10 years, WS was not considered as her diagnosis until she presented with GDM. Biallelic mutations in WFS1 were identified, supporting a diagnosis of classical WS. CONCLUSIONS: The distinct natural history, complications, and differences in management reinforce the importance of distinguishing WS from other forms of diabetes. Recent advances in the genetics and pathophysiology of WS have led to promising new therapeutic considerations that may preserve ß-cell function and slow progressive neurological decline. Insight into the pathophysiology of WS may also inform strategies for ß-cell preservation for individuals with type 1 and 2 diabetes.

Two females with mutations in USP9X highlight the variable expressivity of the intellectual disability syndrome.

The genetic causes of intellectual disability (ID) are heterogeneous and include both chromosomal and monogenic etiologies. The X-chromosome is known to contain many ID-related genes and males show a marked predominance for intellectual disability. Here we report two females with syndromic intellectual disability. The first individual was relatively mild in her presentation with mild-moderate intellectual disability, hydronephrosis and altered pigmentation along the lines of Blaschko without additional congenital anomalies. A second female presented shortly after birth with dysmorphic facial features, post-axial polydactyly and, on follow-up assessment, demonstrated moderate intellectual disability. Chromosomal studies for Individual 1 identified an X-chromosome deletion due to a de novo pericentric inversion; the inversion breakpoint was associated with deletion of the 5'UTR of the USP9X, a gene which has been implicated in a syndromic intellectual disability affecting females. The second individual had a de novo frameshift mutation detected by whole-exome sequencing that was predicted to be deleterious, NM_001039590.2 (USP9X): c.4104_4105del (p.(Arg1368Serfs*2)). Haploinsufficiency of USP9X in females has been associated with ID and congenital malformations that include heart defects, scoliosis, dental abnormalities, anal atresia, polydactyly, Dandy Walker malformation and hypoplastic corpus callosum. The extent of the congenital malformations observed in Individual 1 was less striking than Individual 2 and other individuals previously reported in the literature, and suggests that USP9X mutations in females can have a wider spectrum of presentation than previously appreciated.