Table 4. Mutations in previously uncharacterized genes that affect early morphogenesis.

Mutant	Phenotype	Map position Chr:cM	Gene
Gastrulation arrest
F8	Arrest at e8.0, small embryonic region	7: 53-57.5
W3	Arrest at e8.0, small embryonic region	11: 49-54
dimple (dmpl)	Arrest at e8.0, abnormal primitive streak	6: 37-43
S2	Arrest at e8.0, dead cells in amniotic cavity	15: 39-44
T6	Arrest at e8.0, small embryonic region	5: 18-19
M1ec	Arrest at e7.0	3: 39-41
lazy mesoderm (lzme)	Arrest at e8.0; streak bulges into amniotic cavity	5: 38	Ugdh (12)
Early somite stage arrest wing-shaped neural plate (wsnp)	Deficit in paraxial and axial mesoderm, arrest at e8.5	16: 27-28
limulus (lulu)	Deficit in paraxial and axial mesoderm; arrest at e8.5	1: 63	Epb4.115*
chato	Arrest at e8.5 outside of yolk sac	7: 10-16
mermaid	Deficit in paraxial mesoderm; arrest at e8.5	8: 59-72
kahloista (khlo)	Arrest unturned, small somites	2: 45-47.8	Nap1†
99J1	Arrest unturned	5: 64-80
15A	Deficit in paraxial mesoderm	17: 30-42
1A	Arrest unturned, abnormal heart	11: 52-70
nero	Arrested unturned, no left-right asymmetry; arrest at e9.5	3: 25-35	dolichyl-phosphate β-glucosyltransferase‡
M2	Attest at e9.0, unturned	4: 56.5
e9.5 arrest
19C	Abnormal heart, arrest at e9.5	16: 28-57
38D/p	Swollen lateral plate, abnormal somites	2: 41-48
8A	Small, twisty tail	13: 30-43
Left-right abnormal
3B	Randomized polarity of heart looping, survives past midembryogenesis	7: 10-46.5

^*J.D.L. and K.V.A., unpublished results.

^†A.S.R. and K.V.A., unpublished results.

^‡E.H.F., A.S.R. and K.V.A., unpublished results.