Most of these craniofacial clefts are even rarer and are frequently described as Tessier clefts using the numerical locator devised by Tessier. Classification
Cleft lip and cleft palate is an "umbrella term" for a collection of orofacial clefts. It includes clefting of the upper lip, the maxillary alveolus (dental arch), and the hard or soft palate, in various combinations. Proposed anatomic combinations include:
cleft lip
cleft lip and alveolus
cleft lip, alveolus, and palate
cleft lip and palate (with an intact alveolus)
cleft palate

Prenatal diagnosis
Cleft lip with or without palate is classified as the most common congenital birth defect. It has been noted that the prevalence of orofacial clefts varies by race. The highest number of cases have been recorded among Asians and Native Americans, followed by Europeans, Hispanics and African-Americans. The critical period for cleft development ranges from the 4th to the 12th week of intrauterine life. Clefts of the primary palate develop between the 4th and 7th weeks of intrauterine life, while clefts of the secondary palate develop between the 8th and 12th embryonic weeks. Accurate evaluation of craniofacial malformations is usually possible with the ultrasound scan performed during pregnancy. This is however not a routine procedure according to the American Institute of Ultrasound in Medicine. The accuracy of ultrasonography for prenatal diagnosis of cleft lip +/- palate is dependent on the experience of the sonologist, maternal body type, foetal position, the amount of amniotic fluid and the type of cleft. Prenatal diagnosis enables appropriate and timely education and discussion with parents by the cleft team.
The trial did not show meaningful efficacy and the company has since gone bankrupt.In 2019 Paul Tesar, a professor at Case Western Reserve University, used CRISPR and antisense therapy in a mouse model of Pelizaeus–Merzbacher with success. In 2022 Case Western Reserve University entered a exclusive licensing agreement with Ionis Pharmaceuticals to develop a human treatment for the disorder. See also
The Myelin Project
The Stennis Foundation

References
Further reading
Uhlenberg, Birgit; Schuelke, Markus; Rüschendorf, Franz; Ruf, Nico; Kaindl, Angela M.; Henneke, Marco; Thiele, Holger; Stoltenburg-Didinger, Gisela; Aksu, Fuat; Topaloğlu, Haluk; Nürnberg, Peter; Hübner, Christoph; Weschke, Bernhard; Gärtner, Jutta (August 2004). "Mutations in the Gene Encoding Gap Junction Protein α12 (Connexin 46.6) Cause Pelizaeus-Merzbacher–Like Disease". The American Journal of Human Genetics. 75 (2): 251–260. doi:10.1086/422763. PMC 1216059. PMID 15192806. External links
Pelizaeus-Merzbacher Disease - PMD Foundation
Pelizaeus-Merzbacher Disease. NINDS/National Health Institutes. pmd at NIH/UW GeneTests