Table 3.

Summary and frequency of associated features that can be observed in the main differential diagnoses for HOS

	MIM#	Gene/Locus	Inheritance	Cardiac anomalies	Radial defects	Characteristic clinical features	References
Okihiro syndrome	607323	SALL4	AD	23%	80%	Duane anomaly, renal anomalies	[8, 31]
Fanconi pancytopenia	227650	FA core complex genes	AR, XL	6%	35%	Pancytopenia, growth retardation, microcephaly	[38]
Polydactyly, preaxial type II Syndactyly type IV	174500 and 186200	ZRS locus	AD	–	100%	Isolated pre-axial polydactyly with or without triphalangeal thumbs, mirror image polydactyly	[39]
Valproate embryopathy	–	–	sporadic	14–26%	30%	Developmental delay, neural tube defects, vertebral defects, hypospadias, cleft palate	[40, 41]
VACTERL association	192350	–	sporadic	40–80%	40–50%	Vertebral defects, anal atresia/stenosis, cardiac anomalies, tracheo-Esophageal fistula, renal anomalies, limb defects	[42]
Townes-Brockes syndrome	107480	SALL1	AD	9–40%	50–90%	Anal atresia, ears malformations, deafness, triphalangeal thumbs, renal anomalies	[43]
TAR syndrome	274000	RBM8A	AR	15–30%	100%	Thrombocytopenia, preserved thumbs, lower limbs defects	[44, 45]
Nager syndrome	154400	SF3B4	AD	15%	100%	Mandibulofacial dysostosis, deafness	[46]
LADD syndrome	149730	FGF10, FGFR2, FGFR3	AD	-	95%	Lacrymal ducts atresia, ears malformations, deafness, abnormal teeth, thumb anomalies	[47, 48]
Roberts syndrome	268300	ESCO2	AR	26%	100%	Growth retardation, craniofacial malformations, upper and lower limbs reduction defects	[49, 5, 50]