OMIM ID:
Heimler Syndrome 1
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Some patients have mottling of the retinal pigment and features of macular dystrophy.
Systemic Features
Primary dentition seems to be normal but secondary teeth have generalized enamel hypoplasia. Severe bilateral sensorineural hearing loss has been diagnosed in the first or second year of life. The toenails have transverse ridges (Beau lines) and the fingernails exhibit leukonychia.
Due to the small number of reported families, there is some uncertainty regarding the specificity of the clinical features among the Heimler 1 and Heimler 2 syndromes.
Genetics
Inheritance
Biallelic mutations in the PEX1 gene (7q21.2) are responsible for this syndrome.
Heimler Syndrome 2 (616617) seems to be a unique disorder of peroxisome biogenesis resulting from biallelic mutations in the PEX6 gene.
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.