M2 Disturbance in Development
Lesson 2.1: Heritable Malformations
Teratology= The study of different disturbances that occur during embryonic
and fetal development.
Teratogens = chemical, physical, and biological agents that cause
developmental disturbances
Anomalies = disturbances of development that involve an organ or a portion of
an organ.
Monsters = disturbance of development that involves several organs and
causes great distortion of the individual
Anomalies: Heritable Malformations
Heritable defects: mode of inheritance is according to Mendelian laws of
inheritance
results of definite elements in the germinal makeup
some have dominant characteristics, majority are recessive
effects of defects vary lethal vs non-lethal
Lethal Heritable Defects
Dexter cattle Shortleggedness: when mated inter se or among themselves,
never breed true
→ 1:2:1 ratio:
→ one bulldog (always stillborn): two Dexter (shortleggedness): one kerry
(normal)
Dwarfism in Hereford Cattle: latent lethal defect
Simple, autosomal, recessive gene
M2 Disturbance in Development 1
, F1 → 50% calves dwarf-free-gene carriers; 50% normal.
F2→ dwarf-gene-carrier female+ dwarf-gene carrier male dwarfs accdg to
characteristics of Mendelian ratio
Atresia ani: associated with the complete closure of the ascending colon in the
pelvic flexure region
descendants of Percheron stallion imported into Ohio from Java
common thoroughbred; result of autosomal recessive inheritance
Non-lethal Hereditable Defects
Cryptorchidism: undescended testicles; found retroperitoneally in abdomen;
inguinal canal. -Cryptorchid production animals: Undesirable breeders →
testicular hypoplasia.
Scrotal hernia
Deafness in white Collies not just confined w/ white collies but also seen in
other white breeds
Assoc with pigmentation patterns; merle gene (Collie, Shetland, etc.) and
piebald gene (Bulldog, Beagle etc)
Heritable Blood defects
Hemophilia →→coagulation defect transmitted thru female carriers; sex-linked
recessive character
gene causing trait or the disorder is located on X chromosomes
Hemophilia A: inherited deficiency of functional coagulation factor VIII;
horses, cattle, dogs, and cats
Hemophilia B: inherited deficiency of functional coagulation factor IX;
recognized in dogs and cats
Congenital (Erythropoietic) Porphyria: defect in the formation of hemoglobin;
inherited metabolic defect in heme synthesis
uroporphyrinogen III cosynthetase
"Pink tooth"
M2 Disturbance in Development 2
Lesson 2.1: Heritable Malformations
Teratology= The study of different disturbances that occur during embryonic
and fetal development.
Teratogens = chemical, physical, and biological agents that cause
developmental disturbances
Anomalies = disturbances of development that involve an organ or a portion of
an organ.
Monsters = disturbance of development that involves several organs and
causes great distortion of the individual
Anomalies: Heritable Malformations
Heritable defects: mode of inheritance is according to Mendelian laws of
inheritance
results of definite elements in the germinal makeup
some have dominant characteristics, majority are recessive
effects of defects vary lethal vs non-lethal
Lethal Heritable Defects
Dexter cattle Shortleggedness: when mated inter se or among themselves,
never breed true
→ 1:2:1 ratio:
→ one bulldog (always stillborn): two Dexter (shortleggedness): one kerry
(normal)
Dwarfism in Hereford Cattle: latent lethal defect
Simple, autosomal, recessive gene
M2 Disturbance in Development 1
, F1 → 50% calves dwarf-free-gene carriers; 50% normal.
F2→ dwarf-gene-carrier female+ dwarf-gene carrier male dwarfs accdg to
characteristics of Mendelian ratio
Atresia ani: associated with the complete closure of the ascending colon in the
pelvic flexure region
descendants of Percheron stallion imported into Ohio from Java
common thoroughbred; result of autosomal recessive inheritance
Non-lethal Hereditable Defects
Cryptorchidism: undescended testicles; found retroperitoneally in abdomen;
inguinal canal. -Cryptorchid production animals: Undesirable breeders →
testicular hypoplasia.
Scrotal hernia
Deafness in white Collies not just confined w/ white collies but also seen in
other white breeds
Assoc with pigmentation patterns; merle gene (Collie, Shetland, etc.) and
piebald gene (Bulldog, Beagle etc)
Heritable Blood defects
Hemophilia →→coagulation defect transmitted thru female carriers; sex-linked
recessive character
gene causing trait or the disorder is located on X chromosomes
Hemophilia A: inherited deficiency of functional coagulation factor VIII;
horses, cattle, dogs, and cats
Hemophilia B: inherited deficiency of functional coagulation factor IX;
recognized in dogs and cats
Congenital (Erythropoietic) Porphyria: defect in the formation of hemoglobin;
inherited metabolic defect in heme synthesis
uroporphyrinogen III cosynthetase
"Pink tooth"
M2 Disturbance in Development 2
