Seckel syndrome, or microcephalic
primordial dwarfism
Primordial dwarfism (PD) is a form of dwarfism that results in a smaller body size in all stages of life beginning from before birth. More specifically, primordial dwarfism is a diagnostic category including specific types of profoundly proportion ...
(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 can ...
nanosomic disorder. Inheritance is
autosomal recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
.
It is characterized by
intrauterine growth restriction
Intrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...
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
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 ...
, narrow bird-like face with a beak-like nose, large eyes with down-slanting
palpebral fissure
The palpebral fissure is the elliptic space between the medial and lateral canthi of the two open eyelids. In simple terms, it is the opening between the eyelids. In adult humans, this measures about 10 mm vertically and 30 mm horizontally.
Var ...
s,
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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
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 signifi ...
.
A mouse model has been developed.
This mouse model is characterized by a severe deficiency of
ATR ATR may refer to:
Medicine
* Acute transfusion reaction
* Ataxia telangiectasia and Rad3 related, a protein involved in DNA damage repair
Science and mathematics
* Advanced Test Reactor, nuclear research reactor at the Idaho National Laboratory, ...
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 ...
.
Symptoms and signs
Symptoms include:
*
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 signifi ...
(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 are ...
3 and
18. One form of Seckel syndrome can be caused by mutation in the gene encoding the
ataxia telangiectasia and Rad3-related 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 (1900–1960). The synonym Harper's syndrome was named after
Rita G. Harper.
See also
*
Koo-Koo the Bird Girl
References
External links
*
{{Nucleus diseases
Congenital disorders
Growth disorders
Syndromes affecting head size
Syndromes affecting stature
Syndromes with intellectual disability
Rare syndromes