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Craniosynostosis

Craniosynostosis is the result of the skull sutures halting in growth too soon in development. Craniosynostosis is one the most abundant forms of skull abnormalities for 1 in 25,000 birthed babies (Craniosynostosis genetics,2011). It can affect the digital skeleton bones, skull bones, spinal bones, cardiac bones, or organ bones. The syndrome is associated with several genes but predominantly the mutations have been reported from the fibroblast growth receptor genes. More than 180 different syndromes are associated with craniosynostosis (Craniosynostosis genetics,2011). Secondary effects of this mutation can cause blurred vision and pressure to the body. Many of the inheritance patterns are found to be autosomal dominant. In the study of the molecular genetics of this disorder, fibroblast growth factor genes account for at least 25% of the 180 syndromes associated with craniosynostosis (Craniosynostosis genetics,2011). Three disorder that relate to the specific FGFR3 receptor includes Muenke Syndrome, Crouzon syndrome with acanthosis nigricans (CAN), and Achondroplasia (Craniosynostosis genetics,2011). Symptoms of Muenke syndrome include a larger head diameter, a flattened head, and asymmetrical distortion, and development delay. Most of the patients with this one suffers hearing loss. CAN causes progression of acanthosis, dark skin pigmentation in folds of the skin and thickening of skin layers. Achondroplasia found in FGFR3 mutations include a halt in growth by ossification of the bone cartilages, this results to have short limbs in comparison with the rest of the body (Craniosynostosis genetics,2011). One way to permanently treat this disorder is to perform strip craniectomy, which is described as removing a strip of the bone and replacing it with a fused suture. This surgery can only be performed at a young age, less than 5 months old. After surgery a cranial helmet can be worn for long periods of time to assist craniosynostosis proper development. A more invasive approach can also be performed. This is typically only tested on babies at least 6 moths of age. The incision would be into the cranial bones and then reshaped to the correct proportion of bone. The skull is then held in place with absorbable plates and suture screws. Typically, the procedure has been very effective for the affected patients with little recovery time.

SADDAN (severe achondroplasia with developmental delay and acanthosis nigricans)

SADDAN is a very rare genetic disorder caused by mutation of a growth factor receptor 3 mutation. It is very similar to craniosynostosis because they both exhibit bone distortion from a young age. Bones of the skeleton and brain is affected in growth severely with patients who have SADDAN. Those who are affected with SADDAN generally have achondroplasia, darkened skin pigmentation, and the arms and legs of patients who carry this disease appear to have dwarfism due to the bowing of limbs (Genetics Home Reference,2012). The ribs and collar bone are distorted in an unusual shape, the ribs appear to be shorter in length and the collar bone has some extra curvature associated (Craniosynostosis genetics,2011). If the brain is affected than there is a higher risk of development of seizures. The fibroblast growth factor gene codes instructions of brain and bone development to proteins (Genetics Home Reference,2012). Mutations of this gene can cause the proteins to be overactive and develop un-ordinarily. Most of every case related to SADDAN are random mutations of the FGFR3 gene, even more specifically Lys650Met, which is a specific portion of the gene (Genetics Home Reference,2012). This disease is also an autosomal dominant disorder, meaning either mother or father can pass it on and it is found on a non-sex chromosome. Only one copy is required for mutation to occur. There are forms of treatment out there for SADDAN, Somatotropin, a growth hormone, has shown growth of height and length of bones in patients (Genetics Home Reference,2012). Certain cases can have a surgical procedure to try and eliminate the curvature.

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(2011). Craniosynostosis genetics: The mystery unfolds. Indian journal of human genetics, 17(2), 48-53.

(2012). SADDAN - Genetics Home Reference - NIH. (n.d.). Retrieved from https://ghr.nlm.nih.gov/condition/saddan#definition