Trisomy 8

Doubled An entire arm or more

Doubled less than a whole arm

Trisomy 8, also known as Warkany syndrome 2 (named after the pediatrician Joseph Warkany, 1902-1992 ), is a chromosomal specificity on the basis of a genomic mutation in the genetic material of chromosome 8 three times ( trisom ) instead of the usual two times ( disomic ) is present in some or all cells of the body of man.

Usually there is a mosaic trisomy 8, wherein only a portion of the cells has the additional chromosome, while there is a cell line with the normal disomic chromosome set. This parallel existence of several karyotypes within an organism is referred to as genetic mosaic. The karyotype of the mosaic trisomy 8 is 46XX/47XX 8 8 or 46XY/47XY.

Rare is the free trisomy 8, in which in all body cells, the extra chromosome 8 can be demonstrated ( karyotype: 47xx or 47XY 8 8).

Frequency of occurrence

Trisomy 8 is one of the comparatively rare chromosome features. It occurs sporadically ( sporadic, random), and there are about 120 cases documented. Mostly trisomy 8 is a mosaic before ( mosaic trisomy 8 / trisomy 8 mosaic syndrome). Both boys and girls can be born with trisomy 8.

Common signs before birth (prenatal )

As part of the ever-evolving possibilities of prenatal tests ( prenatal diagnosis ) are with the time some specific features have been documented, which can be relatively frequently found in unborn children with trisomy 8.

The Note characters together in the presence of trisomy 8 may indicate the unborn child, particularly in combination, and which are sometimes to be seen by ultrasound studies include, for example:

• Cardiac defect

• Malformations of the kidney, renal pelvis extension

• Skeletal abnormalities ( Tetramelie )

• Curvature of the spine with outer bulge forward ( scoliosis, lordosis, kyphosis )

• Two or more consecutive vertebrae are completely or partially fused together (block vertebrae)

• Slight bend of the small finger in the direction of ring finger ( clinodactyly ) with simultaneous shortening of tendons and tendon sheaths that make not possible a full extension of each finger ( camptodactyly )

• A comparatively small mouth - chin region ( mandibular retrognathia ) with a shortening of the mandible

• Kurzfingrigkeit ( brachydactyly )

• Narrow ilium

• Absence or malformation of the kneecaps (aplasia or hypoplasia of the patella)

• Accumulation of fluid in the neck region (large nuchal translucency )

None of these symptoms, however, is meaningful enough for a definite diagnosis, even not if some of the special features in combination.

A diagnosis is still solely by examining the chromosomes even possible. Prenatally are available as methods in particular amniocentesis and chorionic villus sampling are available and which these processes subsequent chromosome analysis. Especially in the chorionic villus sampling must be considered that a mosaic trisomy 8 may also occur placental limited, and carries the baby no fetal mosaic in itself and also in the other chromosome analysis mosaics not always be detected.

Common signs after birth ( postnatal)

After birth, most babies find with trisomy 8 different physical characteristics that make a so-called presumptive diagnosis possible. These include, for example:

• Congenital joint stiffness ( arthrogryposis )
• Commonly spina bifida occulta
• Special features of the soles of the feet ( particularly conspicuous corrugations of the soles / Plantarfurchen )
• A comparatively large distance between the first and second toe (sandals gap / sandals furrow )
• Many and deep furrows in the palms ( Palmarfurchen )
• Simian crease ( about 75 out of 100 children )
• Comparatively low set, large and long ears
• Underdeveloped ( hypoplastic ) fold, which is located opposite the ear edge ( antihelix )
• High forehead
• Short neck
• Narrow, sloping shoulders
• Special Features of the number and width of the ribs
• Supernumerary ( accessory ) nipples ( nipples )
• Cleft palate
• Full, thick lips, everted ( everted ) lower lip
• Comparatively smaller interpupillary distance ( hypotelorism )
• Drooping of one or both eyelids, the upper eyelid is more frequently affected (ptosis )

• Squint (strabismus )

• Broad nose, often upward facing nostrils ( nares )

• Often above average weight

• Increased risk of tumors

• Mild to moderate cognitive disability

As differential diagnoses other syndromes come with arthrogryposis in question.

Course

Trisomy 8 is not incurable, only the symptoms can be treated. The clinical picture is quite variable especially in the mosaic trisomy 8 and there are also known people for whom there are hardly any abnormalities.

A forecast for the physical development is dependent on which physical features are present in which form and how they are treated and how they are treated.

The cognitive impairments are generally classified as mild to moderate, in people with the mosaic trisomy 8 are often lighter and highly variable in the expression. With a significantly lower proportion trisomer cells also reaching the usual intelligence is possible.

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