Case1875(M.C.) Female, 22yo died, Irish
CasePresentingHPOs HP:0001263, HP:0001249, HP:0001250, HP:0002650, HP:0002625, HP:0005625, HP:0002857, HP:0000545, HP:0000276, HP:0000275, HP:0000218, HP:0000678, HP:0002878, HP:0001695, HP:0002240
(Developmental delay, Intellectual disability, Seizures, Scoliosis, Deep vein thrombosis, Osteoporosis of vertebrae, Genu valgum, Myopia, Long face, Narrow face, High palate, Crowded teeth, Respiratory failure, Cardiac arrest, Enlarged liver)
HPOsFreeText Diagnosed with homocystinuria after exam for developmental delay at 13mo. Patient had severe intellectual disability and seizures. At 14yo she had surgery for scoliosis, postsurgery she had a popliteal vein thrombosis. In addition to osteoporosis of the spine, she had genu valgum and myopia. The patient also had a long and narrow face, high-arched palate and crowded teeth. Respiratory failure and cardiac arrest at 22yo likely due to overuse of antiasthmatic medication.
(PMID:20329304): She was delivered normally at term, weighed 3kg, made uncomplicated neonatal progress, no history of convulsions,reached early milestones at expected times but did not sit up until 13mo. On report she was well fed and well developed, but with persistent shadow in right upper load on roentgenogram, enlarged liver of normal consistence, spleen was not palpable, negative neurological exam, mental age was 9mo. Aortogram was negative for vascular abnormalities in upper left chest. Skull and long bones were normal but osteoporosis of the spine was detected by roentgenogram.
CaseNotHPOs HP:0001083
(Lens dislocation)
NotHPOsFreeText no malar flush, lens displacement, or skeletal deformity on exam at 13mo.
CasePreviousTesting Plasma homocysteine was 45μM pretreatment. Pyroxidine treatment reduced those levels to trace amounts. In patient fibroblasts, no CBS protein was detect on Western blot and CBS assay detected no activity. (PMID: 20329304): "Full hemogram, routine urine analysis, liver function tests, serum ion and iron-binding capacity, plasma magnesium, serum calcium, inorganic phosphate, fasting blood sugars, blood urea nitrogen, and bone marrow examination were all normal". Strong positive on cyanide nitroprusside, heavy homocysteine spot on chromatogram of urinary amino acids.
CaseMethod1 PCR
CaseMethod2 Sanger
CaseGenotypingMethod Created a bacteria expression system in E.coli by substituting one of three fragments of (PCR amplified)patient cDNA into WT CBS sequence already subcloned in expression plasmids. Bacteria were screened based on which ones did not have CBS activity. Those that did not have activity were thought to have LOF variants in CBS. Plasmids containing the inactivating fragments, one cut with NcoI/XmaI and another cut with Bpu1102/BstX, were sequenced.
Variant 1. NM_000071.2:c.715G>A (p.Glu239Lys),
- NM_000071.2:c.233C>G (p.Pro78Arg);3. NM_000071.2:c.306G>C (p.Lys102Asn) - 2&3 in cis, compound heterozygous
ClinVar 1. n/a, 2. 188988;3. 188989
CAID 1. CA410600501
gnomAD 1. not in gnomAD, 2. MAF=0.0001631(Other), no homozygotes, 3. MAF=0.0001630(Other), no homozygotes
CaseAddInfo n/a
CasePMIDs 20329304