OMIM ID:
Stickler Syndrome, Type II
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Virtually all (85%) patients have a nonprogresssive axial myopia. The vitreous degeneration has a beaded pattern without the veils of type I, claimed by some to be important in the distinction of the two types. Paravascular lattice retinopathy is seen in 38% of patients and 64% have cataracts, sometimes with wedge opacities similar to those in type I Stickler syndrome. Nearly half (42%) of patients are reported to have retinal detachments.
Systemic Features
Hearing loss occurs early and many individuals (80%) eventually require hearing aids. Midline clefting is present frequently with bifid uvula, a highly arched palate, or an actual cleft palate. Joint laxity is common.
Genetics
Inheritance
There are reasons to classify type II Stickler syndrome as a unique disorder apart from type I (108300). In addition to phenotypic evidence (vitreoretinal disease, amount of hearing loss, and degree of epiphyseal disease), mutation in two different genes are involved. Type II results from a mutation in the COL11A1 (1p21) and type I (108300) in COL2A1. Both types are inherited in autosomal dominant patterns.
Type IV (614234) with vitreoretinal changes, myopia, and a high risk of retinal detachment is inherited in an autsomal recessive pattern.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission