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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID
Dhcr7tm1Fdp
targeted mutation 1, Forbes D Porter
MGI:2181641
Summary 2 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
hm1
Dhcr7tm1Fdp/Dhcr7tm1Fdp involves: 129S4/SvJae MGI:3613050
ht2
Dhcr7tm1Fdp/Dhcr7tm2Fdp involves: 129S4/SvJae MGI:3621459


Genotype
MGI:3613050
hm1
Allelic
Composition
Dhcr7tm1Fdp/Dhcr7tm1Fdp
Genetic
Background
involves: 129S4/SvJae
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Dhcr7tm1Fdp mutation (0 available); any Dhcr7 mutation (27 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• homozygotes die during their first day of life, most probably as a result of their failure to feed

behavior/neurological
• homozygous mutant pups fail to suckle, as shown by absence of milk in their stomachs
• hand-fed mutant pups are able to swallow formula; however, their swallowing movements lack the typical rhythmic sucking/swallowing pattern observed in wild-type pups
• mutant pups exhibit general weakness in the absence of gross limb, skeletal, renal, adrenal or CNS abnormalities
• mutant pups exhibit hypotonia and decreased movement in the absence of gross limb or skeletal malformations
• hypotonia is already evident at birth and does not appear to be secondary to lack of feeding
• mutant newborns never vocalize alarm

homeostasis/metabolism
• mutant newborns with no nasal openings display cyanotic episodes consistent with obligate nasal breathing
• mutant pups display a 1678-fold increase in serum 7-dehydrocholesterol (7-DHC) levels relative to wild-type pups; in addition, tissue 7-DHC levels are elevated 250-, 265-, 250-, 791- and 2003-fold in cortex, midbrain, kidney, liver and muscle, respectively (J:68084)
• 8-Dehydrocholesterol (an isomer of 7-DHC) is also markedly elevated in serum and similar tissue samples (J:68084)
• 7-dehydrodesmosterol (7-DHD) is accumulated in brain whereas desmosterol levels are markedly reduced in the cortex and midbrain of mutant pups (J:68084)
• 1-day old mice exhibit a striking localization of residual 7-dehydrocholesterol and cholesterol in the cerebellum and brainstem compared to wild-type mice that show diffuse cholesterol throughout the cerebellum, however normal localization of sterol metabolites is seen at E16-19 (J:165301)
• 7-dehydrocholesterol levels are about 8-fold higher in the cerebellum and brainstem than in controls (J:165301)
• mutant pups exhibit significantly reduced cholesterol levels in serum, cortex, midbrain, kidney, liver and muscle relative to wild-type pups

craniofacial
• 9% of mutant pups exhibit a cleft palate characterized by elevation of the palatal shelves but failure of the secondary palate to close in the midline
• 30% of mutant pups retain a nasal plug in an otherwise normally formed nose
• 9% of mutant pups lack an identifiable nasal opening

growth/size/body
• 9% of mutant pups exhibit a cleft palate characterized by elevation of the palatal shelves but failure of the secondary palate to close in the midline
• 30% of mutant pups retain a nasal plug in an otherwise normally formed nose
• 9% of mutant pups lack an identifiable nasal opening
• at birth, the average weight for mutant pups is 1.11 0.10 g vs 1.44 0.18 g for wild-type pups
• homozygotes exhibit intra-uterine growth retardation which becomes more pronounced during the last 2 days of gestation

respiratory system
• 30% of mutant pups retain a nasal plug in an otherwise normally formed nose
• 9% of mutant pups lack an identifiable nasal opening
• hand-feeding of mutant pups is precluded by aspiration, with dye-labeled formula staining the trachea, bronchi and lung parenchyma; however, no pharynx or trachea malformations are observed
• mutant lungs display diffuse alveolar atelectasis

nervous system
• mutant brains are small, but brain weights are proportional to body weight and show no increased apoptosis
• mutant frontal cortex neurons show a normal response to the neurotransmitter gamma-amino-n-butyric acid (GABA); however, the response of these same neurons to exogenous glutamate (24 M) is significantly reduced
• impaired glutamate response does not appear to be due to altered expression of glutamate receptor subunits in mutant cortex

renal/urinary system
• mutant pups display a dilated bladder with meconium detected in the colon

digestive/alimentary system
• 9% of mutant pups exhibit a cleft palate characterized by elevation of the palatal shelves but failure of the secondary palate to close in the midline

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
Smith-Lemli-Opitz syndrome DOID:14692 OMIM:270400
J:68084 , J:165301




Genotype
MGI:3621459
ht2
Allelic
Composition
Dhcr7tm1Fdp/Dhcr7tm2Fdp
Genetic
Background
involves: 129S4/SvJae
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Dhcr7tm1Fdp mutation (0 available); any Dhcr7 mutation (27 available)
Dhcr7tm2Fdp mutation (0 available); any Dhcr7 mutation (27 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• about 25% of heterozygous embryos are lost before E13.5 when crosses involve mice homozygous for Dhcr7tm2Fdp and heterozygous for Dhcr7tm1Fdp, possibly the result of a maternal effect in the homozygous parent

nervous system
• brain parenchymal volume is significantly reduced between 2 and 12 months of age
• ventricular dilation is seen at 3, 5, and 10 months of age
• seen in 12 of 16 homozygotes
• seen in 12 of 16 homozygotes
• rarely partial agenesis of the corpus callosum is seen

limbs/digits/tail
• second and third toe syndactyly is seen on at least 1 limb in 64% of mice and on 40% of all limbs display this phenotype

homeostasis/metabolism
• at P1 and 6 weeks of age, dehydrocholesterol levels are significantly increased in the central nervous system, liver and kidney
• at P1, cholesterol levels are decreased in the central nervous system, liver and kidney, however levels are similar to wild-type by 6 weeks

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
Smith-Lemli-Opitz syndrome DOID:14692 OMIM:270400
J:106758





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Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB), Gene Ontology (GO)
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last database update
05/10/2022
MGI 6.19
The Jackson Laboratory