<unk>  (NCS) is a syndrome that presents as an extreme form of developmental delay, with the defining characteristic being neoteny of the patient. It was named in 2017 by Dr. Richard F. Walker, who discovered several genes implicated in the syndrome. Prior to 2015, when whole genome sequencing was used to identify some genes involved in NCS, the condition was labelled "Syndrome X" when it was first discovered in Brooke Greenberg. Thereafter, others afflicted with the developmental symptoms were sought out in order to find common genetic aberrations that could provide clues as to cause. To date, seven human females have been diagnosed with NCS. In five patients, coding de novo mutations were found in five different genes which fall into similar functional categories of transcription regulation and chromatin modification.
Neotenic complex syndrome
Primrose syndrome
Dressler syndrome
Brain fag syndrome
Wunderlich syndrome
Michels Caskey syndrome
TAN syndrome
Saal Bulas syndrome