<unk> , or microcephalic primordial dwarfism (also known as bird-headed dwarfism, Harper's syndrome, Virchow–Seckel dwarfism and bird-headed dwarf of<unk>  is an extremely rare congenital nanosomic disorder. Inheritance is autosomal recessive. 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, receding mandible and intellectual disability. A mouse model has been developed. This mouse model is characterized by a severe deficiency of ATR protein. These mice suffer high levels of replicative stress and DNA damage. Adult<unk>  mice display accelerated ageing. These findings are consistent with the DNA damage theory of aging.
Seckel syndrome
Meckel–Gruber syndrome
Familial multiple intestinal atresia
Ackerman syndrome
Van Gogh syndrome
Hartnup disease
Silver–Russell syndrome
Scheuermann's disease