Table 1.

Features Associated with Mutations in IFIH1

Feature	SMS	AGS	Overlap
Short dental roots/early loss of permanent teeth	+
Muscular weakness	+
Aortic calcification	+
Unusual face	+
Psoriasis	+
Hallux valgus	+
Osteopenia of hands/feet	+
Wide medullary cavities of the phalanges	+
Subluxation of joints	+
Thick neurocranium	+
Congenital microcephaly		+
Calcification of white matter		+
Periventricular calcification		+
Quadriplegia/rigidity of legs		+
Irritability		+
Hepatosplenomegaly		+
Lymphadenopathy		+
Thrombocytopenia		+
High signal in the periventricular and deep white matter on T2 weighted imaging		+
Cerebral atrophy		+
Hypertonia		+
Regression		+
Developmental delay	+	+	+
Hypotonia	+	+	+
Glaucoma	+	+	+
Elevated levels of interferon signature genes	+	+	+
Chilblains		+	+
Basal ganglia calcification	+	+	+

AGS, Aicardi–Goutieres Syndrome; SMS, Singleton–Merten syndrome.