Microdeletion 1p36 is probably the most common terminal microdeletion with a frequency of 1:5,000 to 1:10,000. Most patients have a moderate to severe developmental disorder with severe impairment of expressive language, muscle hypotonia, and growth retardation. External features include: a large anterior fontanel that closes late, deep-set eyes, horizontal eyebrows, broad nasal root, hypoplastic midface, low-set dysplastic ears, accentuated pointed chin, brachy- and camptodactyly, short feet. Obesity and hyperphagia are described in some patients. Congenital heart defects are present in about 70% and noncompaction cardiomyopathy in 23%. Almost all patients present with abnormal ECG, and nearly half also have seizures. Visual and hearing disturbances are also present in more than half of the patients.
Microdeletion 1p36 is usually detected by subtelomeric diagnosis or increasingly by CMA (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.
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