Seckel syndrome, or microcephalic primordial dwarfism (also known as bird-headed dwarfism, Harper's syndrome, Virchow–Seckel dwarfism and bird-headed dwarf of Seckel) is an extremely rare

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities c ...

nanosomic disorder. Inheritance is autosomal recessive. It is characterized by intrauterine growth restriction and postnatal

dwarfism Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dw ...

with a small head, narrow bird-like face with a beak-like nose, large eyes with down-slanting palpebral fissures, receding

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...

and

intellectual disability Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...

. A mouse model has been developed. This mouse model is characterized by a severe deficiency of ATR protein. These mice have high levels of replicative stress and

DNA damage DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA da ...

. Adult Seckel mice display accelerated ageing. These findings are consistent with the

DNA damage theory of aging The DNA damage theory of aging proposes that aging is a consequence of unrepaired accumulation of naturally occurring DNA damage. Damage in this context is a DNA alteration that has an abnormal structure. Although both mitochondrial and nuclear DN ...

Symptoms and signs

Symptoms include: *

(more than half of the patients have an IQ below 50) *

microcephaly Microcephaly (from New Latin ''microcephalia'', from Ancient Greek μικρός ''mikrós'' "small" and κεφαλή ''kephalé'' "head") is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it ...

* sometimes

pancytopenia Pancytopenia is a medical condition in which there is significant reduction in the number of almost all blood cells (red blood cells, white blood cells, platelets, monocytes, lymphocytes, etc.). If only two parameters from the complete blood coun ...

(low blood counts) *

cryptorchidism Cryptorchidism, also known as undescended testis, is the failure of one or both testes to descend into the scrotum. The word is from Greek () 'hidden' and () 'testicle'. It is the most common birth defect of the male genital tract. About 3% of ...

in males * low birth weight * dislocations of pelvis and elbow * unusually large eyes * blindness or visual impairment * large, low-set ears * small chin due to receded lower jaw

Genetics

It is believed to be caused by defects of genes on

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

3 and 18. One form of Seckel syndrome can be caused by mutation in the gene encoding the

ataxia telangiectasia and Rad3-related Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of t ...

protein () which maps to chromosome 3q22.1-q24. This gene is central in the cell's DNA damage response and repair mechanism. Types include:

Diagnosis

Treatment

History

The syndrome was named after German-American physician

Helmut Paul George Seckel Helmut is a German name. Variants include Hellmut, Helmuth, and Hellmuth. From old German, the first element deriving from either ''heil'' ("healthy") or ''hiltja'' ("battle"), and the second from ''muot'' ("spirit, mind, mood"). Helmut may refer ...

(1900–1960). The synonym Harper's syndrome was named after

Rita G. Harper Rita may refer to: People * Rita (given name) * Rita (Indian singer) (born 1984) * Rita (Israeli singer) (born 1962) * Rita (Japanese singer) * Eliza Humphreys (1850–1938), wrote under the pseudonym Rita Places * Djarrit, also known as Rita, a ...

References

External links

* {{Nucleus diseases Congenital disorders Growth disorders Syndromes affecting head size Syndromes affecting stature Syndromes with intellectual disability Rare syndromes