aiysha
Forum Senior
Topics: 31
Posts: 133
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A 23year old G2P1 woman has noted minimal fetal movements at 18 weeks. an ultrasound shows fetal limbs are shortened. at 30 weeks gestation a still born fetus is delivered .A postmortem radiograph reveals extensive long bone , rib and pelvic fractures. autopsy reveals normal internal organs.a mutation involving gene encoding for which of following protiens is most likely to produce this findings:
1)fibrillin
2)fibroblast growth factor receptor 3
3)retinoblastoma
4)neurofibromin
5)type 1 collagen
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| Ivil
Forum Senior
Topics: 8
Posts: 169
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Ans 5) Type I collagen. Baby has Type II Osteogenesis Imperfecta which is fatal within 1yr if not still born.
Type I
Collagen is normal but not of a high enough quantity:
Bones fracture easily, especially before puberty
Loose joints
Poor muscle tone
Discolouration of the sclera (whites of the eyes)
Early loss of hearing
IA and IB are distinguished by the absence/presence of dentinogenesis imperfecta (characterized by opalescent teeth.) (Absent in IA, present in IB.)
Type II
Collagen is not of a sufficient quality or quantity
Most cases die within the first year of life due to respiratory failure or intracerebral hemorrhage
Severe respiratory problems due to underdeveloped lungs
Severe bone deformity and small stature
Type III
Collagen quantity is sufficient but is not of a high enough quality
Bones fracture easily, sometimes even before birth
Bone deformity, often severe
Respiratory problems possible
Short stature, spinal curvature and barrel-shaped rib cage
Loose joints
Poor muscle tone in arms and legs
Discolouration of the sclera Early loss of hearing
Type III is distinguished amongst the other classifications as being the "Progressive Deforming" type, wherein a neonate presents with mild symptoms at birth and develops the aforementioned symptoms throughout life. Lifespan may be normal, albeit with severe physical handicapping.
Type IV
Collagen quantity is sufficient but is not of a high enough quality
Bones fracture easily, especially before puberty
Short stature, spinal curvature and barrel-shaped rib cage
Bone deformity is mild to moderate
Discolouration of the sclera Early loss of hearing
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