Your patient is a 2-year-old male named Justin. He is suffering from hypotonia (decreased muscle tone), weakness and growth failure, and is unable to walk. His mother has just brought him into the emergency room from the family beach house, where they have been spending the summer, because he has had a seizure. X-rays indicate that the toddler is suffering from rickets, which is a result of a nutritional deficiency of Vitamin D. But his mother insists that her son’s diet is not Vitamin D-deficient. He drinks three glasses of milk a day, and his diet also includes meat and eggs. A simplified scheme of Vitamin D metabolism is shown to the left. The chemical name of active Vitamin D is 1α, 25-dihydroxycholecalciferol, and it is synthesized via the pathway shown. Catalysts, both in the form of enzymes and ultraviolet light, are required for Vitamin D synthesis. The two main sources of active Vitamin D are diet and sunlight. Food supplemented with “Vitamin D” usually contains cholecalciferol (Vitamin D 3 ). In the liver, dietary cholecalciferol is converted to 25-dihydroxycholecalciferol. Next, in the kidney, that chemical is converted to active Vitamin D. Sunlight is also responsible for producing Vitamin D. The skin contains a precursor, 7-dehydrocholesterol. In the presence of ultraviolet light, which acts as a catalyst, a ring-opening reaction occurs, which is followed by the spontaneous conversion of this intermediate to Vitamin D 3 , and this follows the dietary Vitamin D 3 pathway to become active Vitamin D. Active Vitamin D is a steroid-like compound that acts in combination with other hormones to increase the concentration of Ca 2+ via a variety of mechanisms, one of which includes increasing the intestinal absorption of dietary calcium (intestinal absorption of dietary phosphate, a calcium counter-ion, also increases as a result). Calcium ions are required to form hydroxyapatite Ca5 (PO 4 ) 3 OH, the main mineral constituent of bone. You decide to carry out further analysis and take a sample of Justin’s blood. The laboratory results are below: patientNormal RangeSerum Calcium, mg/dL5.18.7-10.1Serum Phosphorous, mg/dL4.22.4-4.3Serum 1alpha, 25-dihydroxycholecalciferol, pg/mL1320-76Serum 25-hydroxycholecalciferol, ng/mL4810-55 After obtaining the results from the laboratory, you suspect that your patient might have a defective enzyme in the Vitamin D synthetic pathway. Which enzyme do you think is defective, and why? Introduction: Your patient is a 2-year-old male named Justin. He is suffering fromhypotonia (decreased muscle tone), weakness and growth failure, and is unable to walk.His mother has just brought him into the emergency room from the family beach house,where they have been spending the summer, because he has had a seizure. X-raysindicate that the toddler is suffering from rickets, which is a result of a nutritionaldeficiency of Vitamin D. But his mother insists that her son's diet is not Vitamin D-deficient. He drinks three glasses of milk a day, and his diet also includes meat and eggs.HOHOHOCHuv radiation(skin)CHspontaneousCH 3CH 3Ca²+(aq)(intestine)CH 3CH3CH 3CH 37-dehydrocholesterol(diet)CH 3CH₂CH 3-CH 3cholecalciferol(Vitamin D3)•CH 325-hydroxylase(liver)0₂Ca²+(82)(blood)HO1a-hydroxylase(kidney)HOCHCH3CH₂CH3CH 3CH₂OHCas (PO )3OH)(bone)-CH 3CH 3 OH25-hydroxy-cholecalcife rol- CH 3CH 3 OH1a,25-dihydroxy-chole calcife rol(Active Vitamin D)A simplified scheme ofVitamin D metabolism isshown to the left. Thechemical name of activeVitamin D is la, 25-dihydroxycholecalciferol,and it is synthesized viathe pathway shown.Catalysts, both in the formof enzymes and ultravioletlight, are required forVitamin D synthesis. Thetwo main sources of activeVitamin D are diet andsunlight.Food supplemented with"Vitamin D" usuallycontains cholecalciferol(Vitamin D3). In the liver,dietary cholecalciferol isconverted to 25-dihydroxycholecalciferol.Next, in the kidney, thatchemical is converted toactive Vitamin D.Sunlight is alsoresponsible for producing Vitamin D. The skin contains a precursor, 7-dehydrocholesterol. In the presence ofultraviolet light, which acts as a catalyst, a ring-opening reaction occurs, which isfollowed by the spontaneous conversion of this intermediate to Vitamin D3, and thisfollows the dietary Vitamin D3 pathway to become active Vitamin D.2+Active Vitamin D is a steroid-like compound that acts in combination with otherhormones to increase the concentration of Ca²+ via a variety of mechanisms, one ofwhich includes increasing the intestinal absorption of dietary calcium (intestinalabsorption of dietary phosphate, a calcium counter-ion, also increases as a result).Calcium ions are required to form hydroxyapatite Ca5(PO4)3OH, the main mineralconstituent of bone.You decide to carry out further analysis and take a sample of Justin's blood. Thelaboratory results are below:PatientSerum Calcium, mg/dL5.1Serum Phosphorous, mg/dL4.2Serum 1a, 25-dihydroxycholecalciferol, pg/mL 13Serum 25-hydroxycholecalciferol, ng/mL48Normal Range8.7-10.12.4-4.320-7610-551. After obtaining the results from the laboratory, you suspect that your patient mighthave a defective enzyme in the Vitamin D synthetic pathway. Which enzyme do youthink is defective, and why?

Question

Your patient is a 2-year-old male named Justin. He is suffering from hypotonia (decreased muscle tone), weakness and growth failure, and is unable to walk. His mother has just brought him into the emergency room from the family beach house, where they have been spending the summer, because he has had a seizure. X-rays indicate that the toddler is suffering from rickets, which is a result of a nutritional deficiency of Vitamin D. But his mother insists that her son’s diet is not Vitamin D-deficient. He drinks three glasses of milk a day, and his diet also includes meat and eggs. A simplified scheme of Vitamin D metabolism is shown to the left. The chemical name of active Vitamin D is 1α, 25-dihydroxycholecalciferol, and it is synthesized via the pathway shown. Catalysts, both in the form of enzymes and ultraviolet light, are required for Vitamin D synthesis. The two main sources of active Vitamin D are diet and sunlight. Food supplemented with “Vitamin D” usually contains cholecalciferol (Vitamin D 3 ). In the liver, dietary cholecalciferol is converted to 25-dihydroxycholecalciferol. Next, in the kidney, that chemical is converted to active Vitamin D. Sunlight is also responsible for producing Vitamin D. The skin contains a precursor, 7-dehydrocholesterol. In the presence of ultraviolet light, which acts as a catalyst, a ring-opening reaction occurs, which is followed by the spontaneous conversion of this intermediate to Vitamin D 3 , and this follows the dietary Vitamin D 3 pathway to become active Vitamin D. Active Vitamin D is a steroid-like compound that acts in combination with other hormones to increase the concentration of Ca 2+ via a variety of mechanisms, one of which includes increasing the intestinal absorption of dietary calcium (intestinal absorption of dietary phosphate, a calcium counter-ion, also increases as a result). Calcium ions are required to form hydroxyapatite Ca5 (PO 4 ) 3 OH, the main mineral constituent of bone. You decide to carry out further analysis and take a sample of Justin’s blood. The laboratory results are below:  patientNormal RangeSerum Calcium, mg/dL5.18.7-10.1Serum Phosphorous, mg/dL4.22.4-4.3Serum 1alpha,  25-dihydroxycholecalciferol, pg/mL1320-76Serum 25-hydroxycholecalciferol, ng/mL4810-55 After obtaining the results from the laboratory, you suspect that your patient might have a defective enzyme in the Vitamin D synthetic pathway. Which enzyme do you think is defective, and why? Introduction: Your patient is a 2-year-old male named Justin. He is suffering fromhypotonia (decreased muscle tone), weakness and growth failure, and is unable to walk.His mother has just brought him into the emergency room from the family beach house,where they have been spending the summer, because he has had a seizure. X-raysindicate that the toddler is suffering from rickets, which is a result of a nutritionaldeficiency of Vitamin D. But his mother insists that her son's diet is not Vitamin D-deficient. He drinks three glasses of milk a day, and his diet also includes meat and eggs.HOHOHOCHuv radiation(skin)CHspontaneousCH 3CH 3Ca²+(aq)(intestine)CH 3CH3CH 3CH 37-dehydrocholesterol(diet)CH 3CH₂CH 3-CH 3cholecalciferol(Vitamin D3)•CH 325-hydroxylase(liver)0₂Ca²+(82)(blood)HO1a-hydroxylase(kidney)HOCHCH3CH₂CH3CH 3CH₂OHCas (PO )3OH)(bone)-CH 3CH 3 OH25-hydroxy-cholecalcife rol- CH 3CH 3 OH1a,25-dihydroxy-chole calcife rol(Active Vitamin D)A simplified scheme ofVitamin D metabolism isshown to the left. Thechemical name of activeVitamin D is la, 25-dihydroxycholecalciferol,and it is synthesized viathe pathway shown.Catalysts, both in the formof enzymes and ultravioletlight, are required forVitamin D synthesis. Thetwo main sources of activeVitamin D are diet andsunlight.Food supplemented with&#34;Vitamin D&#34; usuallycontains cholecalciferol(Vitamin D3). In the liver,dietary cholecalciferol isconverted to 25-dihydroxycholecalciferol.Next, in the kidney, thatchemical is converted toactive Vitamin D.Sunlight is alsoresponsible for producing Vitamin D. The skin contains a precursor, 7-dehydrocholesterol. In the presence ofultraviolet light, which acts as a catalyst, a ring-opening reaction occurs, which isfollowed by the spontaneous conversion of this intermediate to Vitamin D3, and thisfollows the dietary Vitamin D3 pathway to become active Vitamin D.2+Active Vitamin D is a steroid-like compound that acts in combination with otherhormones to increase the concentration of Ca²+ via a variety of mechanisms, one ofwhich includes increasing the intestinal absorption of dietary calcium (intestinalabsorption of dietary phosphate, a calcium counter-ion, also increases as a result).Calcium ions are required to form hydroxyapatite Ca5(PO4)3OH, the main mineralconstituent of bone.You decide to carry out further analysis and take a sample of Justin's blood. Thelaboratory results are below:PatientSerum Calcium, mg/dL5.1Serum Phosphorous, mg/dL4.2Serum 1a, 25-dihydroxycholecalciferol, pg/mL 13Serum 25-hydroxycholecalciferol, ng/mL48Normal Range8.7-10.12.4-4.320-7610-551. After obtaining the results from the laboratory, you suspect that your patient mighthave a defective enzyme in the Vitamin D synthetic pathway. Which enzyme do youthink is defective, and why?

Accepted Answer

Hypotonia :As the name suggests, hypotonia is an underlying condition where muscles have a reduced…

	patient	Normal Range
Serum Calcium, mg/dL	5.1	8.7-10.1
Serum Phosphorous, mg/dL	4.2	2.4-4.3
Serum 1alpha, 25-dihydroxycholecalciferol, pg/mL	13	20-76
Serum 25-hydroxycholecalciferol, ng/mL	48	10-55