SFMS is an X-linked disease by chromosome Xq13. X-linked diseases map to the human X chromosome because this syndrome is an X chromosome linked females who have two chromosomes are not affected but because males only have one X chromosome, they are more likely to be affected and show the full clinical symptoms. This disease only requires one copy of the abnormal X-linked gene to display the syndrome. Since females have two X chromosomes, the effect of one X chromosome is recessive and the second chromosome masks the affected chromosome. Affected fathers can never pass this X-linked disease to their sons but affected fathers can pass the X-linked gene to their daughters who has a 50% chance to pass this disease-causing gene to each of her children. Since females who inherit this gene do not show symptoms, they are called carriers. Each of the female's carrier's son has a 50% chance to display the symptoms but none of the female carrier's daughters would display any symptoms. Some patients with SFMS have been founded to have a mutation of the gene in the ATRX on the X chromosome, also known as the Xq13 location. ATRX is a gene disease that is associated with other forms of X-linked mental retardation like Alpha-thalassemia/mental retardation syndrome, Carpenter syndrome, Juberg-Marsidi syndrome, and spastic paraplegia. It is possible that patients with SFMS have Alpha-thalassemia/mental retardation syndrome without the affected hemoglobin H that leads to Alphathalassemia/ mental retardation syndrome in the traditionally recognized disease.
Smith–Fineman–Myers syndrome
McKittrick-Wheelock syndrome
Senior–Løken syndrome
Kearns–Sayre syndrome
Schwartz–Matsuo syndrome
Lujan–Fryns syndrome
Beare–Stevenson cutis gyrata syndrome
Fanconi–Bickel syndrome