Table 3. [FGFR1 Allelic Disorders]. - GeneReviews®

Type of FGFR1 Germline Pathogenic Variant	Phenotype
Loss of function ¹	Hartsfield syndrome
Normosmic isolated GnRH deficiency
Kallmann syndrome
Kallmann syndrome w/additional features incl digital anomalies that are distinct from split-hand/foot malformation; mild expression of HPE (e.g., corpus callosum agenesis, central incisor)
Septo-optic-like dysplasia
Gain of function	Pfeiffer syndrome (See FGFR Craniosynostosis Syndromes Overview.)

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