Klippel–Feil syndrome (KFS), also known as cervical vertebral fusion syndrome, is a rare congenital condition characterized by the abnormal fusion of any two of the seven bones in the neck (cervical vertebrae). : 578  It results in a limited ability to move the neck and shortness of the neck, resulting in the appearance of a low hairline.The syndrome is difficult to diagnose, as it occurs in a group of patients affected with many different abnormalities who can only be unified by the presence of fused or segmental cervical vertebrae. KFS is not always genetic and not always known about on the date of birth. The disease was initially reported in 1884 by Maurice Klippel and André Feil from France. In 1919, in his Doctor of Philosophy thesis, André Feil suggested another classification of the syndrome, encompassing not only deformation of the cervical spine, but also deformation of the lumbar and thoracic spine. Signs and symptoms
KFS is associated with many other abnormalities of the body, hence thorough evaluation of all patients with fused cervical vertebrae at birth is required. Furthermore, it is unclear whether KFS is a unique disease, or if it is one part of a spectrum of congenital spinal deformities.KFS is usually diagnosed after birth.
The embryo, then the fetus and then the baby will have what is called a 45,X/46,XY constitution. This is called a
mosaic karyotype because, like tiles in mosaic floors or walls, there is more than one type of cell.There are many chromosomal variations that cause the 45,X/46,XY karyotype, including malformation (isodicentricism) of the Y chromosomes, deletions of Y chromosome or translocations of Y chromosome segments. These rearrangements of the Y chromosome can lead to partial expression of the SRY gene which may lead to abnormal genitals and testosterone levels. Diagnosis
Identification of 45,X/46,XY karyotype has significant clinical implications due to known effects on growth, hormonal balance, gonadal development and histology. 45,X/46,XY is diagnosed by examining the chromosomes in a blood sample. The age of diagnosis varies depending on manifestations of disease prompting reason for cytogenetic testing. Many patients are diagnosed prenatally due to fetal factors (increased nuchal fold, or abnormal levels of serum), maternal age or abnormal ultrasounds, while others will be diagnosed postnatal due to external genital malformation. It is not uncommon for patients to be diagnosed later in life due to short stature or delayed puberty, or a combination of both.45,X/46,XY mosaicism can be detected prenatally through amniocentesis however, it was determined that the proportion of 45,X cells in the amniotic fluid cannot predict any phenotypic outcomes, often making prenatal genetic counselling difficult. Management
See also
Gonadal dysgenesis
Mosaic (genetics)
Turner syndrome

References


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