De Grouchy syndrome is the name given to two types of chromosomal mutation in humans, the various losses (deletions ) pieces of the short ( 18p - ) or long arm ( 18q - ) of chromosome 18 are due. There arise avoiding partial monosomy; the critical chromosomal region 18q23 locus is located in the.
The syndrome is divided into two types de Grouchy syndrome I and de Grouchy syndrome II, which are summarized under the term deletion syndromes of chromosome 18. They go hand in hand with each different malformation complexes. A combination of features of both types syndrome is detectable in humans with the 18- R syndrome.
The first description under scientific aspects took place in the years 1963 and 1964. Since then, more than 100 case studies documented.
The phenotypic expression is very different, not all symptoms occur in all affected people, and they can be designed individually different. This is presumably (also) on the length of each piece of the lost chromosome, although accurate correlations could not be assigned. Conclusions about the severity of their symptoms and the development of an affected child are therefore not possible. Certainly, the nature and severity of individual symptoms present plays an important role in the prognosis. In some cases, the influence of an established cell mosaic on the severity of their symptoms can not be excluded. In such a parallel genetic mosaic are two cell lines, one as usual and is striking (here with the corresponding deletion ). Depending on the proportion of normal cells, the symptoms may be milder.
De Grouchy syndrome I
The type I of the syndrome is also known under the synonyms 18p syndrome, 18p deletion syndrome, 18p deletion syndrome, del ( 18p ) syndrome, chromosome 18p, monosomy, monosomy 18p and 18p partial monosomy. There is a slice loss ( deletion ) of the short arm ( 18p ) of chromosome 18.
The children fall after birth heaped on by a low birth weight and somatic hypotrophy, decreased muscle tone ( hypotonia ), often quite large hands with short fingers, sometimes simian crease, lateral deflection of a phalanx ( clinodactyly ), and syndactyly of some toes. Heart failure and intestinal position anomalies ( Malrotationen ) are possible.
Sometimes some of these and other symptoms are not immediately apparent, but are formed only during the first years of life can be seen from. Among the features described in children with type I of the syndrome include relatively large ears, partly there is a closure ( atresia ) or narrowing (stenosis ) of the ear canals before, funnel chest, special features in the area of the brain and head (heaped Kurzköpfigkeit with special rounding of the head / brachycephaly, holoprosencephaly at one of ten children, some with monocular vision / Monophthalmie, absence of the olfactory bulb / Arrhinenzephalie, premature closure of the cranial sutures ), special features around the eye area ( malformation of the eye muscles / ocular dysmorphism, malformations of the bony orbits / orbitare dysmorphia, comparatively small eyes / microphthalmia, quite widely spaced eyes / hypertelorism, unusually narrow palpebral fissures / blepharophimosis with upward or downward Lidachsenstellung, crescent-shaped fold of skin at the inner corners of eyes / epicanthus medialis, drooping of one or both upper eyelids / ptosis, cataract, glaucoma, coloboma, strabismus / strabismus, nystagmus / nystagmus), unusually long thumb.
Also described are a significant underdevelopment ( hypoplasia) and / or a return of the mandible ( distal occlusion / mandibular retrognathia ), excessive width of the mouth opening ( Macrostomia ), droopy corners of the mouth, peculiarities of the teeth or tooth development (later tooth eruption, partly missing tooth systems, vulnerability for dental caries ), the presence of a narrowing ( stenosis) or a closure ( atresia ) of the posterior nares, which connect the nasal cavity to the throat, a retarded bone age ( thus slower growth ), spinal curve (scoliosis ), humpback ( kyphosis ). An inflammation of the thyroid ( thyroiditis ), Graves' disease, immune deficiencies, autoimmune symptoms, lack of immunoglobulin A, mellitus in adolescence type 1 diabetes and in girls the absence of menstruation ( primary amenorrhea ) may occur.
In the course of the child's performance shows a cognitive disabilities whose degree can vary from easy to very hard.
De Grouchy syndrome II
In type II syndrome there is a deletion of the long arm 18q22 -23. Again, the children fall through somatic hypotrophy and in the further development of pituitary -induced growth retardation, probably due to a growth hormone insufficiency ( GH ) insufficiency on. Microcephaly, hypotonia, a narrowing or blockage of the ears, eye malformations, peculiarities of the teeth, cognitive disability and immune deficiencies associated with autoimmune symptoms can occur such as the type I.
18- R- syndrome
If a child is a ring chromosome 18 with deletion of the long and the short arm ( r18 ) prior to show combinations of features of the de Grouchy syndrome I and II
Also, because the deletion syndromes of chromosome 18 very rare and the symptoms are variable and therefore difficult to assign a chromosomal analysis is the diagnostic tool of choice. A differential diagnosis, eg for Cerebro - oculo - Fazio - Skeletal Syndrome can help in narrowing down.
Since it is a chromosomal cause, a causal cure is not possible, so that the reduction applies to the symptomatic treatment of individual symptoms.
The deletion is usually in a simple piece of loss on chromosome 18
In rare cases, translocation of chromosome 18 to another chromosome that is originated from an originally reciprocal and balanced shape in which it has arrived in correspondence with a piece of transfer between two chromosomes, or to a pericentric inversion no piece loss and without phenotypic effects. People with this balanced chromosomal specificity are clinically silent and can propagate. The probability that there will be a Inbalance in the genotype of the child at fertilization is possible if the mother or father a reciprocal translocation or an inversion is present. In the course of meiosis, it can happen in this constellation that both translocation chromosomes are inherited or a so-called crossing over occurs in the inverted section. The formerly good balance of the genome is thus disturbed, and it comes to a piece of loss, which leads the child to the respective deletion syndrome.
In most cases, the deletion occurs spontaneously. Is the chromosome image ( karyotypes ) of both parents inconspicuous or the affected child has a ring chromosome 18, there are no indications of an increase in the probability again to beget a child with one of the deletion syndromes of chromosome 18.
If the child has a deletion syndrome with translocation or inversion, and can be seen corresponding balanced abnormalities in the karyotype of the mother or father, it increases the likelihood that a recurrence of a Inbalance of the genome at conception of another child. Parents have the opportunity to seek human genetic advice before and during pregnancy and to take for antenatal screening for the presence of a deletion in the child appropriate test methods of prenatal diagnosis to complete. For a positive result and permits them to have a termination of pregnancy make on medical indications.
A clinically inconspicuous child whose mother or father has a balanced translocation or inversion, this may have inherited and would in this case also a potential carriers of the trait.