Seckel syndrome
Medical condition
From Wikipedia, the free encyclopedia
Seckel syndrome, or microcephalic primordial dwarfism (also known as bird-headed dwarfism, Harper's syndrome, Virchow–Seckel dwarfism and bird-headed dwarf of Seckel[1]) is an extremely rare congenital nanosomic disorder. Inheritance is autosomal recessive.[2] It is characterized by intrauterine growth restriction and postnatal dwarfism with a small head, narrow bird-like face with a beak-like nose, large eyes with down-slanting palpebral fissures,[3] receding mandible and intellectual disability.
| Seckel syndrome | |
|---|---|
| Other names | Harper's syndrome |
| |
| Boy with Seckel syndrome (left) | |
| Specialty | Medical genetics |
| Causes | defects of genes on chromosome 3 and 18. |
A mouse model has been developed.[4] This mouse model is characterized by a severe deficiency of ATR protein.[4] These mice have high levels of replicative stress and DNA damage. Adult Seckel mice display accelerated aging.[4] These findings are consistent with the DNA damage theory of aging.
Symptoms and signs
Symptoms include:[5]
- intellectual disability (more than half of the patients have an IQ below 50)
- microcephaly
- sometimes pancytopenia (low blood counts)
- cryptorchidism 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 3 and 18. One form of Seckel syndrome can be caused by mutation in the gene encoding the ataxia telangiectasia and Rad3-related protein (ATR) which maps to chromosome 3q22.1–q24. This gene is central in the cell's DNA damage response and repair mechanism.
Types include:[6]
Diagnosis
There are 4 criteria for diagnosis:[7]
- Congenital Dwarfism and postnatal growth retardation
- Microcephaly, large eyes, beak-like nose, narrow face, retrognathism, malocclusion
- Mental handicap
- Agenesis of the corpus callosum, cerebral cysts
Other abnormalities can be a supportive criteria, such as: anemia, pancytopenia, cleft lip/palate scoliosis or kyphoscoliosis.[8]
Genetic testing can confirm diagnosis.[5]