GAPO syndrome

GAPO syndrome is a rare, autosomal recessive disorder that causes severe growth retardation, and has been observed fewer than 30 times before 2011. GAPO is an acronym that encompasses the predominant traits of the disorder: growth retardation, alopecia, pseudoanodontia (teeth failing to emerge from the gums), and worsening optic atrophy in some subjects. Other common symptoms include premature aging, large, prominent foreheads, and delayed bone aging. GAPO syndrome typically results in premature death around age 30–40, due to interstitial fibrosis and atherosclerosis.“GAPO syndrome | About the Disease | GARD”.

GAPO syndrome was first described in 1947. Since then, fewer than 60 cases have been reported in the medical literature up to the year 2021.“GAPO syndrome | About the Disease | GARD”.

GAPO syndrome is caused by homozygous nonsense or splicing mutations in the ANTXR1 gene located on chromosome 2p13.3. This gene encodes anthrax toxin receptor 1, also known as tumor endothelial marker 8 (TEM8). The inheritance pattern is autosomal recessive, and genetic counseling is recommended for at-risk couples to inform them that each pregnancy carries a 25% risk of having an affected child“GAPO syndrome | About the Disease | GARD”.

GAPO syndrome is a genetic disorder resulting from mutations in the ANTXR1 gene, leading to dysfunctional anthrax toxin receptor 1. Symptoms may begin to appear in infancy or early childhood.“GAPO syndrome | About the Disease | GARD”.

GAPO syndrome is a genetic disease, which means that it is caused by one or more genes not working correctly.Disease-causing variants, or differences, in the following gene(s) are known to cause this disease: ANTXR1“GAPO syndrome | About the Disease | GARD”.

• Growth Retardation: Individuals with GAPO syndrome exhibit slow skeletal formation, resulting in below-average height.
• Alopecia (Hair Loss): Hair is typically thinly dispersed and fragile, often leading to baldness later in life.
• Pseudoanodontia: Tooth growth is stunted, with teeth failing to emerge from the gums or develop normally.
• Progressive Optic Atrophy: Approximately one-third of individuals experience optic nerve atrophy, leading to peripheral vision impairment and difficulty distinguishing colors.
• Facial Features: While not defining, most individuals with GAPO syndrome have coarse facial features, including a large forehead, depressed nose bridges, protruding ears, and thick lips.
• Mental Function: There is no direct correlation between GAPO syndrome and mental retardation, although some cases of co-occurrence have been reported.“GAPO syndrome | About the Disease | GARD”.

Approximately 60 patients with GAPO syndrome have been reported in literature since the first description in 1947.“GAPO syndrome | About the Disease | GARD”.

There are no specific risk factors associated with the development of GAPO syndrome.“GAPO syndrome | About the Disease | GARD”.

There are no established screening programs for GAPO syndrome.“GAPO syndrome | About the Disease | GARD”.

GAPO syndrome has no curative treatment. Management primarily involves ophthalmologic surveillance and addressing symptomatic health problems. Individuals with GAPO syndrome generally have a reduced lifespan, typically living until the fourth to sixth decade of life.“GAPO syndrome | About the Disease | GARD”.

Diagnosis mostly relies on physical and ophtamologic examination. Additionally skin biopsy, cerebral angiography and magnetic resonance imaging contribute to more specific diagnosis.Prenatal diagnosis is not possible from fetal ultrasound (US). In utero growth retardation may be observed on US but is not specific.

There is no curative treatment. Management mostly relies on ophthalmologic surveillance and symptomatic treatment of the multiple health problems.GAPO patients are reported to have a reduced lifespan (until the fourth to sixth decade of life“GAPO syndrome | About the Disease | GARD”.

“GAPO syndrome | About the Disease | GARD”.

• Online Mendelian Inheritance in Man (OMIM) 230740

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