Trichomegaly Plus Syndrome
Patient Information
Characteristics
Background and History
This rare condition is a multisystem disorder involving the eye, mental and physical development, and neurological function. Its genetic origin has not been established.
Clinical Correlations
Infants often have a low birth weight and their physical growth is delayed. Often developmental milestones such as walking, speech, and crawling are achieved late and some children lose these motor functions in the first decade. Most patients have some difficulty with reasoning and understanding while a few have been described as mentally retarded. Peripheral nerves (such as those in the arms and legs) do not work properly leading to weakness in muscles and lack of sensation.
Young children may be abnormally sensitive to light and have difficulty with night vision. Roving or wondering movements of the eyes (nystagmus) are often present. The eye doctor may detect abnormalities in the form of abnormal pigment in the retina as early as 5 years of age. The loss of vision may be severe. The eyelashes are unusually long and the eyebrows are excessively bushy. However, scalp hair is often sparse or even absent.
Growth is delayed throughout life and individuals often end up short in stature. Sexual characteristics are underdeveloped. The constellation of signs and symptoms in most individuals suggest that the pituitary gland does not work properly.
Genetics
Inheritance
Family evidence suggests that this is an inherited autosomal recessive condition but no gene mutation has been found. Couples with one affected child of either sex have a 25% risk of having another such child with each pregnancy.
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
The diagnosis is most likely made sometime in the first decade of life and it requires a team approach among neurologists, pediatricians, and ophthalmologists. The individual signs and symptoms are relatively common and the specific combination of these is required for confirmation. Individuals live to adulthood. Low vision aids should be beneficial in the early stages of this condition.
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