Gene

Cytogenetic band locus

Known and putative functional genomics

SPTLC1 Serine palmitoyltransferase 1

9q22.2/22.31

Patients with severe HSN1 have disease-associated SPTLC1 mutations [4] [7] [15] . Some mutations are implicated in enzyme catalytic promiscuity that leads to accumulation of neurotoxic sphinganines in plasma samples and recombinant HEK293T cells [8] [9] .

TGFBR1 Transforming growth factor, beta receptor 1

9q22

Encoded protein forms heteromeric complex with type II TGF-beta receptors when bound to TGF-beta. Transduces TGF-beta signal from cell surface to the cytoplasm. Mutation in TGFBR1 known to alter TGF-β signaling, promote tumorigenesis and increase risk for Breast cancer [47] [59] .

SHC3 Src homology containing 3 domain

9q22.1

Encodes a docking protein important in signaling pathways regulating cellular proliferation, survival and differentiation. The interaction of SHC3 and Edg3R is important in cancer progression [60] . The SHC3 domain of SPTLC1 may allow crosstalk with EDG3.

Edg3R (S1P3)

Endothelial differentiation G-protein coupled receptor 3

9q22.1 - 22.2

Family of Edg receptors signal cellular proliferation, morphology and are involved in inflammation [61] -[63] . Edg3 signals through G-protein to downstream events of Rho, Ras, PKC and PI3K [64] . The EDG3 and SHC3 genes at 9q22.1 encode proteins whose interaction is implicated in cancer progression [44] [60] .

Patch 1 (PTCH1)

Negative regulator patched 1

9q22.3

One of cytoplasmic receptors for a number of hedgehog proteins implicated in tumorigenesis [41] . A tumor suppressor mutation in PTCH1 is implicated in increased constitutive activity of growth promoting Hedgehog signaling in urothelial carcinoma [65] .