In most of the patients analyzed, researchers identified missense de novo mutations in a set of genes. Mutations in three of these genes (DDX3X, TLK2 and HDAC8) were shared with those found in databases of individuals with developmental delay or autism spectrum disorder. A mutation in one gene (TMEM63B) was identified in a large knockout mouse study as likely to result in disease in humans. In two patients, a small (~150 kb) non-coding region of chromosome X was discovered to have a rare haplotype. This region appears to have regulatory functions (histone acetylation and DNase I hypersensitivity) and is in close proximity to several genes (AP1S2, MRX59, MRXSF, MRXS21, MRXS5 and PGS) involved in mental retardation. The fact that NCS has so far only been found in females may be by chance or may be due to the X linkage of some of the genes and regions potentially responsible for NCS, in which the lack of a healthy copy on a second X chromosome could render the disease lethal in males. Whether or not these mutations contribute to NCS is unclear. Not enough research has been conducted, complicated by the rarity of the syndrome. Many genetic differences were noted to be insignificant, and the effects of mutations in some genes are currently beyond scientific understanding.
Neotenic complex syndrome
Primrose syndrome
Dressler syndrome
Brain fag syndrome
Wunderlich syndrome
Michels Caskey syndrome
TAN syndrome
Saal Bulas syndrome