2p15-16.1 microdeletion is an extremely rare genetic disorder caused by a small deletion in the

short arm In genetics, a locus (plural loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or ...

of human chromosome 2. First described in two patients in 2007, by 2013 only 21 people have been reported as having the disorder in the medical literature.

Presentation

As of 2013, only 21 patients with a 2p15-16.1 microdeletion had been identified. The clinical similarities between the individuals resulted in the classification of a new genetic syndrome. The shared clinical features include moderate to severe intellectual disability and similar facial features including telecanthus, drooping eyelids, downslanting, short palpebral fissures, a prominent nasal bridge, high palate with long, smooth philtrum and an everted lower lip. Some of the patients also had feeding problems in infancy, microcephaly, optic nerve hypoplasia and hydronephrosis, wide-spaced nipples, short stature, cortical dysplasia, camptodactyly and pigeon toe.

Cause

Three of the patients reported had a consistent

proximal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

breakpoint on chromosome 2, but varying

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

breakpoints. The patients have 2p15–16.1 deletions of 5.7

megabases A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DN ...

(Mb), 4.5 Mb, 3.9 Mb, 3.35Mb 3.3Mb and 570 kilobases, respectively. In all 21 patients the deletions are '' de novo'' — neither parent possessed nor transmitted the mutation to the affected individual. One patient is a

genetic mosaic Mosaicism or genetic mosaicism is a condition in multicellular organisms in which a single organism possesses more than one genetic line as the result of genetic mutation. This means that various genetic lines resulted from a single fertilized ...

, having some cells with the deletion and others without.

Affected genes

The largest deletion encompasses approximately 15 protein-coding genes, 6

pseudogene Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by Reverse transcriptase, reverse transcription of an mRNA trans ...

s and a number of other as yet uncharacterised candidates, including: * AHSA2, activator of heat shock 90kDa protein ATPase homolog *

BCL11A B-cell lymphoma/leukemia 11A is a protein that in humans is encoded by the ''BCL11A'' gene. Function The ''BCL11A'' gene encodes for a regulatory C2H2 type zinc-finger protein, that can bind to the DNA. Five alternatively spliced transcript va ...

, B-cell lymphoma/leukemia 11A * C2orf74, Uncharacterized protein C2orf74 * FANCL, E3 ubiquitin-protein ligase FANCL *

KIAA1841 KIAA1841 is a gene in humans that encodes a protein known as KIAA1841 (uncharacterized protein KIAA1841). KIAA1841 is targeted for the nucleus and it predicted to play a role in regulating transcription. Gene Location KIAA1841 is located ...

, Uncharacterized protein KIAA1841 * PAPOLG, Poly(A) polymerase gamma * PEX13, Peroxisomal membrane protein Peroxin-13 * PUS10, Pseudouridylate synthase 10 * REL, C-Rel proto-oncogene protein * SNORA70B, small nucleolar RNA, H/ACA box 70B * USP34, Ubiquitin carboxyl-terminal hydrolase 34 *

VRK2 Serine/threonine-protein kinase VRK2 is an enzyme that in humans is encoded by the ''VRK2'' gene. This gene encodes a member of the vaccinia-related kinase (VRK) family of serine/threonine protein kinases. This gene is widely expressed in human ti ...

, Serine/threonine-protein kinase VRK2 * XPO1, Exportin-1

Diagnosis

Treatment

References

External links

* * Orphanet entry fo
2p15-16.1 microdeletion syndrome
* {{Medicine Autosomal monosomies and deletions Genetic anomalies Syndromes with intellectual disability Syndromes with craniofacial abnormalities Syndromes with microcephaly Syndromes with short stature Syndromes affecting the kidneys Syndromes with dysmelia Chromosomal abnormalities