Joint Laxity, Short Stature, and Myopia
Patient Information
Characteristics
Background and History
This is a recently reported disorder of the skeleton and eye in two consanguineous Saudi families.
Clinical Correlations
Extreme nearsightedness (high myopia), joint laxity, and short stature were found in 5 members of two families. Abnormal curvature of the spine (kyphosis) and dislocation of large joints including the knees, elbows, hips, and ankles occurred in two members of one family. Retinal detachments were found in two of the three brothers in another family. Glaucoma was present in one female who was legally blind. Hearing loss was identified in one member of each of the two sibships.
Developmental defects in certain pigmented structures (colobomas) of the eye were reported in two brothers.
No cognitive impairment was identified among the 5 individuals with this condition.
Genetics
Inheritance
This is an autosomal recessive disorder resulting from a mutation in both members of a specific gene. Each of the apparently normal parents would contribute one mutated gene to the affected offspring with a 50% probability and thus confer a risk of 25% for this condition to each of their future offspring.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
Diagnosis in the newborn is unlikely since most of the signs are apparent later. Myopia is likely present at birth since the length of the eyeball is developmentally increased but specific testing is required to measure this and would be outside of the usual neonatal evaluation.
Nothing is known regarding life expectancy. No treatment has been reported but monitoring eye examinations are recommended with prompt retinal detachment repairs and treatment for glaucoma. Dislocated joints should be treated promptly as well.
Printer Friendly Version: Ctrl/Cmd+P