In patients with semantic anomia, a naming deficit is accompanied by a recognition deficit. Thus, unlike patients with word selection anomia, patients with semantic anomia are unable to select the correct object from a group of objects, even when provided with the name of the target object. Disconnection anomia results from the severing of connections between sensory and language cortices. Patients with disconnection anomia may exhibit modality-specific anomia, where the anomia is limited to a specific sensory modality, such as hearing. For example, a patient who is perfectly capable of naming a target object when it is presented via certain sensory modalities like audition or touch, may be unable to name the same object when the object is presented visually. Thus, in such a case, the patients anomia arises as a consequence of a disconnect between their visual cortex and language cortices.Patients with disconnection anomia may also exhibit callosal anomia, in which damage to the corpus callosum prevents sensory information from being transmitted between the two hemispheres of the brain. Therefore, when sensory information is unable to reach the hemisphere that is language-dominant (typically the left hemisphere in most individuals), the result is anomia. For instance, if patients with this type of disconnection anomia hold an object in their left hand, this somatosensory information about the object would be sent to the right hemisphere of the brain, but then would be unable to reach the left hemisphere due to callosal damage.
However, DBA is characterized by dominant inheritance, and arises from partial loss of ribosomal function, so it is possible that erythroid progenitors are more sensitive to this decreased function, while most other tissues are less affected. Diagnosis
Typically, a diagnosis of DBA is made through a blood count and a bone marrow biopsy. A diagnosis of DBA is made on the basis of anemia, low reticulocyte (immature red blood cells) counts, and diminished erythroid precursors in bone marrow. Features that support a diagnosis of DBA include the presence of congenital abnormalities, macrocytosis, elevated fetal hemoglobin, and elevated adenosine deaminase levels in red blood cells.Most patients are diagnosed in the first two years of life. However, some mildly affected individuals only receive attention after a more severely affected family member is identified.About 20–25% of DBA patients may be identified with a genetic test for mutations in the RPS19 gene. Treatment
Corticosteroids can be used to treat anemia in DBA. In a large study of 225 patients, 82% initially responded to this therapy, although many side effects were noted. Some patients remained responsive to steroids, while efficacy waned in others. Blood transfusions can also be used to treat severe anemia in DBA. Periods of remission may occur, during which transfusions and steroid treatments are not required. Bone marrow transplantation (BMT) can cure hematological aspects of DBA. This option may be considered when patients become transfusion-dependent because frequent transfusions can lead to iron overloading and organ damage. However, adverse events from BMTs may exceed those from iron overloading.