What is 3-M Syndrome?
3-M Syndrome is a very rare congenital pathological condition which is characterized by extremely low birth weight of the infant, extremely short stature, craniofacial abnormalities, and certain skeletal abnormalities.
A child with 3-M Syndrome will have an abnormally long and narrow head and frontal bossing with an extremely prominent forehead. He or she will have a triangular shaped face and abnormally large ears.
Additionally, infants with 3-M Syndrome will also have abnormal teeth where they will be crowded abnormally and the upper and lower teeth may not meet normally.
Infants with 3-M Syndrome will also have certain skeletal abnormalities with extremely thin bones especially of the arms and legs, abnormal bones of the spinal column.
The extent of the physical features are extremely variable and may range from moderate to severe and differ from individual to individual in most of the cases of 3-M Syndrome.
This condition follows an autosomal recessive trait meaning that two copies of the faulty gene with one copy from each parent are required for the child to develop 3-M Syndrome.
What Are The Causes of 3-M Syndrome?
As stated, 3-M Syndrome follows an autosomal recessive trait and the defective gene is inherited from both the parents. The genes believed to be responsible for 3-M Syndrome are the CUL7, OBSL1, and CCDC8 genes. Abnormality in any of these three genes may result in development of 3-M Syndrome.
Some studies have suggested that there are other genes also responsible for the development of this condition and hence researchers believe that not all the patients will have mutations in these three genes if they have 3-M Syndrome.
What Are The Symptoms of 3-M Syndrome?
In majority of the cases, children with 3-M Syndrome will be extremely short in stature. They will have an abnormally low birth weight even though they may not be preterm babies.
Additionally, infants with 3-M Syndrome will have abnormally long and narrow head as a result of premature closure of the fibrous joints between the bones in the skull. Frontal bossing is also one of the presenting features of 3-M Syndrome along with a triangular shaped face.
Large set ears, widely spread lips, and the upper and lower teeth which do not meet together are some of the other features of 3-M Syndrome. In addition, infants with 3-M Syndrome will have abnormally short neck and wide shoulders. Scapular winging is also one of the classic presenting features of 3-M Syndrome.
How is 3-M Syndrome Diagnosed?
In some cases if an ultrasound is conducted prenatally, some of the features of 3-M Syndrome such as growth retardation may be visible and the physician may be able to detect that the child to be born has 3-M Syndrome.
In majority of the cases, 3-M Syndrome is diagnosed shortly after the birth of the child by looking at the extremely low birth weight along with the characteristic features of long and narrow head and broad shoulders.
A thorough clinical evaluation may also be performed to check for any abnormalities that are specific for a condition like 3-M Syndrome. Advanced radiological studies in the form of CT and MRI scan of the brain and other vital structures may clearly show abnormalities within the skull resulting in abnormally long and narrow head which are classic findings for 3-M Syndrome.
Additionally, genetic testing may be done which will clearly show mutation in at least one of the three genes which are the CUL7, OBSL1 or CCDC8 which will confirm the diagnosis of 3-M Syndrome.
How is 3-M Syndrome Treated?
The mainstay of treatment for 3-M Syndrome is purely supportive and symptomatic. This requires a multidisciplinary effort from a team of specialists to include pediatricians, neurologists, neurosurgeons, and orthopedists to evaluate and formulate a treatment plan best suited for the patient. Surgery may be done to correct some of the skeletal and craniofacial abnormalities. Oral surgery may be required to correct the deformities of the teeth associated with 3-M Syndrome.