The 1p36 microdeletion is one of the most common terminal microdeletions and occurs in around 1:5,000 to 1:10,000 people. Intellectual disabilities, distinctive facial features and heart defects are characteristic.
Also called
Other names for this syndrome are:
- Chromosome 1p36 microdeletion syndrome
- Distal monosomy 1p36
- Monosomy 1p36 syndrome
- 1p telomere deletion syndrome
- Del(1)(p36)
- Chromosome 1p36 deletion syndrome, distal, isolated cases
- Deletion 1p36
- Deletion 1pter
- Monosomy 1P36 syndrome
- Monosomy 1p36
- Monosomy 1pter
- Subtelomeric 1p36 deletion
- 1p36 deletion syndrome
Symptoms
Distinctive facial features:
- Small head
- Deep-set eyes
- Straight eyebrows
- Broad flat nose
- Low-set dysplastic ears
- Pointed chin
- Midface hypoplasia
Other symptoms:
- Moderate to severe developmental disorder and intellectual disabilities with delayed or absent speech
- Behavior problems
- Decreased muscle tone (hypotonia)
- Growth retardation with prenatal onset
- Short, bent fingers and toes (brachydactyly and camptodactyly)
- Short feet
- Abnormal ECG and heart defects: congenital heart defects are present in about 70% and noncompaction cardiomyopathy in about 23%
- Seizures in around 50%
- Obesity and hyperphagia (extreme hunger)
- Visual and hearing disturbances in more than half of the patients
Frequency
Microdeletion 1p36 is probably the most common terminal microdeletion, occurring with a frequency of 1:5,000 to 1:10,000.
Cause
1p36 microdeletion syndrome is caused by a microdeletion—the deletion of a small amount of material—from the short arm of chromosome 1. The size of the deletion varies.
Inheritance
Microdeletion 1p36 is usually not inherited. In about 20% of cases, children inherit an unbalanced translocation (a chromosomal rearrangement with loss of genetic material) from a parent that causes the symptoms of 1p36 microdeletion syndrome.
Diagnosis
Microdeletion 1p36 is usually detected by subtelomeric diagnosis or increasingly by chromosomal microarray; in individual cases, it can be diagnosed by light microscopy using a high-resolution banding technique (between 600 and 800 bands) in chromosomal analysis.
Treatment
The treatment of 1p36 microdeletion syndrome includes physical, occupational and speech therapy, as well as medical intervention to manage symptoms.
Differential diagnosis
Differential diagnoses include Angelman, Prader-Willi, Rett and Smith-Magenis syndromes.
References
D’Angelo et al. 2010, Am J Med Genet 152A:102 / Battaglia 2005, Brain Dev 27:358 / Slavotinek et al. 1999, J Med Genet 36:657 / Shapira et al. 1997, Am J Hum Genet 61:642
“Chromosome 1p36 Deletion Syndrome - National Organization for Rare Disorders.” National Organization for Rare Disorders, 27 Jan. 2025, http://rarediseases.org/mondo-disease/chromosome-1p36-deletion-syndrome/. Accessed 29 Jan. 2025.
MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2020 Jun 24]. 1p36 deletion syndrome; [updated 15 Mar. 2024]; Available from: https://medlineplus.gov/genetics/condition/1p36-deletion-syndrome/. Accessed 06 Feb. 2025.
“Orphanet: 1p36 Deletion Syndrome.” Www.orpha.net, www.orpha.net/en/disease/detail/1606. Accessed 06 Feb. 2025.
