Baraitser-Winter Syndrome 2
Patient Information
Characteristics
Background and History
This is a rare heritable condition caused by a gene mutation, not to be confused with Baraitser-Winter Syndrome 1 which is caused by a different mutation. Both conditions can be clinically similar and involve multiple organ systems resulting in significant health problems.
Clinical Correlations
There is considerable variability in signs and symptoms among patients and not all have all of the features. Short stature, small heads, and intellectual disability are common. The eyes appear too far apart, the eyebrows are unusually high, and the eyelids usually droop (ptosis). The eyes including the colored part of the eye (iris) may have physical defects but nothing is known about the level of vision. Imaging of the brain reveals physical malformations. Hearing loss is common.
Genetics
Inheritance
A single mutation in the ACTG1 gene is responsible for this condition. While the expected pattern of inheritance is vertical (autosomal dominant) and would be expected to pass from parent to offspring, in reality all cases occur sporadically. This is not uncommon among autosomal dominant conditions when reproduction of affected individuals is limited.
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 physical and mental alterations are most likely detected by pediatricians but other specialists such as neurologists, neurosurgeons, and ophthalmologists are likely to be consulted. There is no specific treatment available but special education and physical therapy may be helpful.
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