OMIM ID:
Cataracts 46, Juvenile-Onset
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
This type of cataract has been found among the Lehrerleut Hutterites and in the population of the Aland Islands, Finland. It may have its onset in infancy but usually is diagnosed between the ages of 3 to 9 years, beginning as cortical lens opacities and progressing to maturity in 1-3 months. Some individuals have subcapsular opacifications, both anterior and posterior. In early stages there may be a diffuse haze throughout the lens. The degree of opacification can be highly asymmetrical.
Systemic Features
A number of Hutterite patients in the reported pedigree have suffered sudden death presumably of arrhythmogenic origin in the third through fifth decades of life.
Genetics
Inheritance
Homozygous mutations in LEMD2 (6p21.32-p21.31) are responsible for this type of cataract. It is uncertain if sudden death is an association or part of the phenotype resulting from these mutations. However, all except one of the pedigree members experiencing sudden death had cataracts. This feature was not mentioned in the 1985 report of juvenile cataracts in the Hutterite population.
The gene product of LEMD2 is expressed in both the mouse and human lens. Indirect evidence also suggests it plays a role in heart development and cardiomyopathy.
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.