Chromosomal abnormalities range from the loss or addition of an entire chromosome to variations in smaller portions of the genetic sequence on a particular chromosome. The risk of chromosomal abnormalities increases with maternal age, probably due to the processes involved in oocyte maturation. Monosomy is the term used for the presence of a single chromosome in a pair. In addition, each chromosome consists of two parts – a long arm (denoted as q) and a short arm (denoted as p). Meiotic and mitotic processes can sometimes result in the deletion of one of these arms, resulting in partial monosomy.
Causes of monosomy 9p
Monosomy 9p, also known as Alfi’s syndrome or 9pminus (9p-), is a rare genetic disorder that was first recognized in 1968. The disorder occurs when the distal portion of the short arm of chromosome 9 (known as p22-pter) is missing from one of the chromosomes in the pair. According to WebMD, the cause appears to be spontaneous chromosomal alterations early in embryonic development, known as de novo mutation. Due to the rarity of the disorder, not much information is available for families who are dealing with it.
Symptoms of 9pminus
As with other chromosomal abnormalities, the features of children with Alfi’s syndrome include mental retardation, craniofacial deformities and congenital heart defects. Individuals with the disorder may appear to have a number of abnormal body features, including:
- an abnormally shaped forehead, called trigonocephaly
- upward slanting eyelid folds, called palpebral fissures
- midfacial hypoplasia, where the middle of the face seems abnormally flat
- a flattened skull in the back of the head
- extra eyelid tissue, called epicanthic folds, as also seen in individuals with Down’s syndrome
- abnormal ear placement and/or shape
- long philtrum/upper lip
- small mouth, called microstomia
- small jaw, called micrognathia
- high arched palate
- extra digits
Genital defects may also be present, including smaller than normal genitalia in males. Heart defects include patent ductus arteriosus, a condition in which the fetal great vessel does not properly close after birth, interrupting normal blood flow to and from the lungs; ventricular septal defects, sometimes referred to as “holes” in the heart; and pulmonic stenosis. Other defects can include hernia and seizures.
RightDiagnosis provides a list of 68 potential defects based on multiple sources of the signs and symptoms of the loss of the short arm of chromosome 9 in humans.
Treatment and support for Alfi’s syndrome
Individuals with this disorder can survive into adulthood, though the mental impairment will always be present. Patients with more severe defects may not survive childhood or infancy. Treatment of the defects, particularly those of the heart, may alleviate the mortality risk. This type of treatment usually includes surgery. Leukemia and some cancers may be long-term complications of the disorder based on the little research done on the subject.
Because of the rarity of this chromosomal abnormality there is not as much known about it as there is about other disorders. A cure is not available, but the symptoms of the chromosome loss can be treated. If you or a loved one suffer from this condition and are interested in participating in clinical trials or medical research of the disorder, you can search ClinicalConnections for opportunities.