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Rare Genetic Disorders
Alfi’s Syndrome — Monosomy 9p
Alfi’s syndrome is the name given to the collection of symptoms caused by a chromosomal abnormality called monosomy 9p. It is also called 9p- or 9pminus, or 9p deletion syndrome. It occurs in an estimated 1 in 50,000 births and describes the absence of a portion of the “p” arm of chromosome 9. The amount of missing chromosome, which depends on the breakpoint in the sequence, can vary, resulting in variable presentation and symptoms. Due to the rarity of the disorder, not much information is available for families who are dealing with it.
Loss of part of a chromosome
Each chromosome consists of two parts — a long arm (denoted as “q”) and a short arm (denoted as “p”). Meiotic and mitotic processes can sometimes result in the deletion or translocation of one of these arms, resulting in partial monosomy (meaning the presence of only one whole chromosome — there should be two). Monosomy 9p was first recognized in 1968 (though the work wasn’t published until 1973) by Dr. O. Alfi and occurs when the distal portion of the short arm of chromosome 9 is missing from one of the chromosomes in the pair (resulting karyotype, 46,9p-). The cause appears to be spontaneous chromosomal alterations early in embryonic development, known as de novo mutation (which can then be passed along to offspring). The…
