MedGen

Like all CDGs, which are caused by a shortage of precursor monosaccharide phosphate or deficiencies in the glycosyltransferases required for lipid-linked oligosaccharide precursor (LLO) synthesis, CDG Ij is caused by a defect in the formation of DPAGT1, the first dolichyl-linked intermediate of the protein N-glycosylation pathway. For a general discussion of CDGs, see CDG1A (212065). [from OMIM]

Sensorineural deafness with dilated cardiomyopathy is an extremely rare autosomal dominant syndrome described in two families to date and characterized by moderate to severe sensorineural hearing loss manifesting during childhood, and associated with late-onset dilated cardiomyopathy that generally progresses to heart failure. [from ORDO]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]

Amelogenesis imperfecta is an inherited defect of dental enamel formation that shows both clinical and genetic heterogeneity. In the hypoplastic type of AI, the enamel is of normal hardness but does not develop to normal thickness. The thinness of the enamel makes the teeth appear small. Radiographically, enamel contrasts normally from dentin. The surface of the enamel can vary, showing smooth, rough, pitted, or local forms (Witkop, 1988). [from OMIM]

Charcot-Marie-Tooth disease type 1J (CMT1J) is an autosomal dominant sensorimotor peripheral neuropathy characterized by distal muscle weakness and atrophy, as well as distal sensory impairment, predominantly affecting the lower limbs and resulting in gait abnormalities. The age at onset is highly variable, ranging from early childhood to mid-adulthood, and the disorder is progressive, although the severity is also variable. Additional features may include foot deformities, upper limb or hand involvement, and decreased or absent deep tendon reflexes. Electrophysiologic studies tend to show nerve conduction velocities in the demyelinating range, although some patients may have results in the intermediate range, likely reflecting secondary axonal degeneration (summary by Ronkko et al., 2020). For a discussion of genetic heterogeneity of autosomal dominant Charcot-Marie-Tooth disease type 1, see CMT1B (118200). [from OMIM]

A congenital disorder of glycosylation involve disrupted synthesis of the lipid-linked oligosaccharide precursor. [from MONDO]