What is Aase Syndrome?
Aase Syndrome (or Aase-Smith Syndrome II) is a highly infrequent disorder. Individuals with this disorder show a variety of signs and symptoms at birth, characteristic features of which include, congenital hypoplastic anemia and triphalangeal thumbs
Congenital hypoplastic anemia is a condition, in which the population of red blood cells is decreased because of reduced bone marrow production
Triphalangeal thumb is a term meant to denote 3 phalanges (finger bones) in the thumb, as against 2 phalanges in a normally developed thumb
The presence of both congenital hypoplastic anemia and triphalangeal thumbs, are necessary for a clinical diagnosis of Aase Syndrome
The prognosis of this disorder depends upon the severity of the syndrome
Who gets Aase Syndrome?
Aase Syndrome is a rare disorder that is manifested at birth. Current evidence suggests that in some individuals, the condition may be genetic; it being inherited in an autosomal recessive manner. The cause of Aase Syndrome is uncertain, at this point in time
Both the male and female sexes, are equally predisposed towards the syndrome
What are the Risk Factors for Aase Syndrome?
The direct cause for Aase Syndrome is unknown though some cases are known to be genetic. In a majority, the syndrome is not inherited/familial – indicating that it does not run in families. In such cases, if an individual has Aase syndrome, then there does not appear to be an increased risk for the family members
However, there are a few occasions where Aase Syndrome is genetically inherited
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Aase Syndrome?
In a majority of cases, the cause of Aase Syndrome is unknown
There have only been an estimated 20 cases of Aase Syndrome reported in medical literature. Research is still being conducted to establish the origins of the syndrome, to detect the exact genes involved, and patterns of inheritance
In a minority of cases, the condition is an inherited genetic disorder, though location/origin of the specific genetic defect is unknown. Nevertheless, it is known that the disorder is inherited in an autosomal recessive manner, in such cases
What are the Signs and Symptoms of Aase Syndrome?
Individuals with Aase Syndrome demonstrate a variety of physical signs and symptoms. The presence of congenital hypoplastic anemia (very low red blood cell count at birth) and triphalangeal thumbs (3-bones in the thumb, triple-jointed thumbs) is characteristic and important features of Aase Syndrome. Therefore, the condition is also called Congenital Anemia-Triphalangeal Thumb Syndrome.
A diagnosis of Aase Syndrome is usually made, very early in life (typically during infancy). Other signs and symptoms include:
- Delayed growth of the child
- Delayed closure of the fontanels (membranous gaps) of the skull bones
- Narrowing of the shoulders
- Abnormal extension of the joints due to do congenital contractions
- Abnormally formed ears
- Cleft palate
- Drooping of the eyelids
- Pale color of skin
How is Aase Syndrome Diagnosed?
A diagnosis of Aase Syndrome would involve:
Complete physical examination with evaluation of family medical history
Complete blood count will show decreased number of red cells (anemia) and white blood cells (leukopenia)
Individuals with Aase Syndrome may have congenital heart disease. The most common one noted is a ventricular septal defect (VSD). VSD can be diagnosed using echocardiogram diagnostic modality
X-rays of the skeletal system will demonstrate various abnormalities, including triphalangeal thumbs, growth retardation in long bones of the body, and delayed closure of the skull fontanels
Bone marrow biopsy may demonstrate decreased similarity of the bone marrow, which causes hypoplastic anemia and leukopenia
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Aase Syndrome?
A few complications of Aase Syndrome include:
Individuals have reduced ability to carry oxygen in blood because of anemia, due to which they easily tire and become weak
Congenital heart defects can also result in heart failure
Individuals with this syndrome do not have a normal life span; early deaths and stillbirths have been reported with this condition
How is Aase Syndrome Treated?
Treatment measures for Aase Syndrome:
Due to the presence of anemia, patients are treated with packed red blood cell transfusion(s), to help increase the body ability to carry oxygen. Blood transfusions are generally started early; in many instances, the transfusions are given within a child’s first year of life
A bone marrow transplant is also a modality to treat leukopenia and hypoplastic anemia
Steroidal therapy using medications, such as prednisone, is helpful in older individuals. Steroidal therapy is generally not recommended for children less than one year of age because it may affect brain development
Heart defects may be corrected through surgery
How can Aase Syndrome be Prevented?
Aase Syndrome is a very rare condition that is difficult to prevent. The direct cause of this disorder (genetic or otherwise), is not known at this point in time
However, early recognition and treatment can increase an individual’s quality of life
If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
What is the Prognosis of Aase Syndrome?
The prognosis of Aase syndrome depends upon the severity of the syndrome. Individuals with severe forms of the disorder may have a shortened life span
Hypoplastic anemia gradually gets better with time (it may take years), resulting in decreased dependence on blood transfusions. The bone marrow recovery may take many more years
White blood cells (leukocytes) are an integral part of an immune system. Decreased leukocytes (leukopenia) due to decreased production in bone marrow may also cause damaging effects on the body immune system. Depending on the severity of leukopenia, individuals with Aase Syndrome may be prone to a variety of infections. Greater the degree of leukopenia, more severe is the infection
In those with severe congenital heart defects (such as a large ventricular septal defect), heart failure may occur, resulting in early death
Stillbirths have been associated with Aase Syndrome
Symptoms – Aase syndrome
- Mildly slowed growth
- Pale skin
- Delayed closure of fontanelles (soft spots)
- Narrow shoulders
- Triple jointed thumbs, absent or small knuckles, decreased skin creases at finger joints
- Inability to fully extend the joints from birth (congenital contractures)
- Cleft palate
- Deformed ears
- Droopy eyelids
Causes – Aase syndrome
Most cases of Aase syndrome occur without a known reason and are not passed down through families (inherited). However, some cases have been shown to be inherited.
The anemia in Aase syndrome is caused by poor development of the bone marrow, which is where blood cells are formed.
Several genes (RPL5, RPL11, RPL35A, RPS7, RPS10,RPS17, RPS19, RPS24, and RPS26) have been identified whose mutation cause Aase syndrome. These genes provide instructions for making several of the approximately 80 different ribosomal proteins, which are components of cellular structures called ribosomes. Ribosomes process the cell’s genetic instructions to create proteins.
Mutations in any of the genes listed above are believed to affect the stability or function of the ribosomal proteins. Studies indicate that a shortage of functioning ribosomal proteins may increase the self-destruction of blood-forming cells in the bone marrow, resulting in anemia. Abnormal regulation of cell division or inappropriate triggering of apoptosis may contribute to the other health problems that affect some people with aase syndrome.
Prevention – Aase syndrome
As with most genetic diseases there is no way to prevent the entire disease. With prompt recognition and treatment of infections in childhood, the complications of low white blood cell counts may be limited.
Genetic counseling is recommended if you have a family history of the syndrome and wish to become pregnant.
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