Perrault Syndrome
Patient Information
Characteristics
Background and History
This is a complex hereditary condition consisting of at least 5 types caused by mutations in genes. The clinical signs are highly variable, even among sibs of the same family, but most individuals have a combination of hearing loss with various neurological problems affecting limb movements and maintaining balance. Females have underperforming ovaries.
Clinical Correlations
Individuals with hearing loss and various malfunctions of the nervous system may have this syndrome which in females has the additional feature of ovarian dysfunction. Physical growth is often delayed and some mental limitations may be present including learning difficulties, cognitive delays, limb weakness, unsteadiness, and, in some individuals, mental retardation. Sensation is sometimes altered as well. Seizures seem to occur only rarely.
A few patients have limited eye movements when looking around and the eyelids appear to droop. Decreased vision has also been reported.
Genetics
Inheritance
Both autosomal recessive and autosomal dominant patterns of inheritance occur among the 5 types of Perrault syndrome. Parents of recessive cases can expect a recurrence rate of 25% among future children whereas the risk is 50% in dominant cases but few individuals are capable of reproduction.
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
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
The diagnosis of Perrault syndrome is usually suspected some by one year of age when infants fail to achieve normal milestones. Pediatricians and neurologists are likely to make the diagnosis. Brain scans may be needed to document abnormalities such as a small cerebellum. There is no known treatment of the neurological problems and the impact on longevity is unknown.
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