Jacobsen syndrome
Encyclopedia
Jacobsen Syndrome, also known as 11q deletion disorder, is a rare congenital disorder
resulting from deletion of a terminal region of chromosome 11 that includes band 11q24.1. It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems including heart
defects and a bleeding disorder
. The syndrome was first identified by Danish physician Petra Jacobsen, and is believed to occur in approximately 1 out of every 100,000 births.
In addition, patients tend to be shorter than average and have poor psychomotor skills.
The majority of Jacobsen syndrome cases are not familial in nature, resulting from a spontaneous mutation
occurring in a single parental gamete
. However, some instances of familial disease resulting from local chromosome fragility or an unbalanced translocation
have been described.
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
resulting from deletion of a terminal region of chromosome 11 that includes band 11q24.1. It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems including heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
defects and a bleeding disorder
Haemophilia
Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A is the most common form of the disorder, present in about 1 in 5,000–10,000 male births...
. The syndrome was first identified by Danish physician Petra Jacobsen, and is believed to occur in approximately 1 out of every 100,000 births.
Possible characteristics
- Heart defects
- Mild to severe intellectual disabilities
- Low-platelets (thrombocytopeniaThrombocytopeniaThrombocytopenia is a relative decrease of platelets in blood.A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. These limits are determined by the 2.5th lower and upper percentile, so values outside this range do not necessarily indicate disease...
) - Facial/skeletal (dysplasiaDysplasiaDysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...
) - Wide-set eyes caused by trigonocephalyTrigonocephalyTrigonocephaly is a congenital condition of premature fusion of the metopic suture leading to a triangular shaped forehead. The merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion...
- Folding of the skin near the eye (epicanthus)
- Short, upturned nose (anteverted nostrils)
- Thin lips that curve inward
- Displaced receding chin (retrognathia)
- Low-set, misshapen ears
- Permanent upward curvature of the pinkie and ring fingers (camptodactylyCamptodactylyCamptodactyly is a medical condition involving fixed flexion deformity of the interphalangeal joints of the little finger. This involves permanent flexure of one or more phalanges...
) - Large great toes/Hammer toesHammer toeA hammer toe or contracted toe is a deformity of the proximal interphalangeal joint of the second, third, or fourth toe causing it to be permanently bent, resembling a hammer...
In addition, patients tend to be shorter than average and have poor psychomotor skills.
The majority of Jacobsen syndrome cases are not familial in nature, resulting from a spontaneous mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
occurring in a single parental gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
. However, some instances of familial disease resulting from local chromosome fragility or an unbalanced translocation
Chromosomal translocation
In genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes, the occurrence of which is common in cancer. It is detected on...
have been described.
Sources
- European Chromosome 11 Network - Support group for patients with chromosome 11 disorders, their families and relatives
- Orthoseek - Specializes in pediatric orthopedics and pediatric sports medicine