Talk:18p-

Test from article
Monosomy 18p is also known as De Grouchy syndrome type 1. De Grouchy syndrome is a rare congenital medical condition caused by an abnormality involving chromosome 18. It has two forms, classified as type 1 or type 2, depending on the nature of the genetic lesion.

De Grouchy syndrome type 1 involves deletion of genes from the short arm of the chromosome (18p). This condition, first described in the 1960s, has been described in over 100 case reports. De Grouchy syndrome type 1 is also called “monosomy 18p”, “18p deletion syndrome”, or “18p- syndrome.” For more information, see The Chromosome Research and Registry, http://chromosome18.org/Conditions/18p/tabid/126/Default.aspx.

Research has shown that some individuals with 18p- need hormone supplementation, and some have demonstrated Septo-Optic Dysplasia. Individuals with 18p- have also been diagnosed with adrenal insufficiency, a life-threatening condition, and hypothyroidism, which can cause mental retardation if left untreated in children. All individuals diagnosed with 18p- should receive care from an endocrinologist familiar with the condition.


 * I don't believe this is copied, and if it isn't I'm not able to find references for the two types and for the hormone supplementation. It doesn't appear to be explicitly mentioned on the chromosome 18 registry page-- §hanel  22:55, 15 April 2010 (UTC)

None of this information is copied. Please excuse me as I am unfamiliar with how to make Wiki changes; if I am not doing this correctly, I apologize. I am not a doctor; I am just trying to help other families who are affected by 18 p deletions. It is important to relate that kids with this don't all have MR. I am the parent of a twelve year old who happens to have 18p- (AKA deGrouchy Syndrome I, monosomy 18p, etc.). She has normal-advanced IQ, and is reading above grade level. She also has panhypopituitarism and Septo-Optic Dysplasia (small optic nerves, non-functioning pituitary).

Our child almost died in infancy, because the doctors did not know about the connection between 18p- and panhypopituitarism/Combined Pituitary Hormone Deficiency--CPHD). If your child is diagnosed with 18p-, please, please insist on testing--and retesting--for pituitary problems--it could save your child's life, and also prevent MR! Low thyroid in infancy can cause MR (used to be called "cretinism"), and adrenal insufficiency can cause death due to adrenal crisis.

The Chromosome 18 Research Society suggests that an endocrinologist should test once a year, as deficiencies can develop at any time. Testing at birth is not sufficient. This relationship between chromosome 18p- and the pituitary deficiencies has been documented for a long time (see references, below--there are many others, that I didn't include due to time constraints), but for some reason it is still not referenced in many medical resources.

References: Chromosomal abnormalities and CPHD. A variety of chromosomal anomalies have been reported in individuals with hypopituitarism including del 18p11 [Boudailliez et al 1983], 18p-, the balanced translocation X;18 (q22.3; q23) [Larizza et al 1993], and paracentric inversion of the short arm of chromosome 18 [Siegel et al 1995].

Gantz I, Tashiro T, Barcroft C, et al. Localization of the genes encoding the melanocortin-2 (adrenocorticotropic hormone) and melanocortin-3 receptors to chromosome 18p 11.2 and 20q 13.2–q 13.3 by fluorescence in situ hybridization. Genomics 1993; 18 (1): 166–7. | Article | PubMed | ISI | ChemPort |

For more up-to-date information, see Chromosome 18 Research Society, http://www.chromosome18.org/Portals/C18/Documents/Brochures/18pFreq20Sep2009.pdf

Much of the old research for 18p- and mental retardation was based on very small sample populations that were also the severest cases, and these studies continue to be cited and assumed to be definitive. When our child was an infant, we were told by a geneticist that our child would have an IQ of around 50--which was totally wrong! (She is normal to advanced IQ.) Some of the research was even based on studies of dead infants. How do you test the IQ of a dead infant? Answer: You don't. The geneticist just assumed that the child must have low IQ, due to deformities. It is also very difficult to test IQ of individuals who have limited speech due to dystonia, hypotonia, facial differences, and delayed development, so it is possible that in some cases,individuals were assumed to have MR, when in fact they were simply limited in expressive speech. Thank you for your patience with my attempts at conveying this information. — Preceding unsigned comment added by Eaglesnesthome (talk • contribs) 22:58, 10 July 2011 (UTC)