Thyroid resistant nephrotic syndrome caused by mutation in gene encoding.
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thyroid resistant nephrotic syndrome gene mutation encoding protein
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thyroid hormone resistance nephrotic syndrome gene mutation
Now I have strong textbook evidence. Let me clarify the exact question being asked - "thyroid resistant nephrotic syndrome" most likely refers to steroid-resistant nephrotic syndrome in the context of a thyroid-related question, OR it could be asking about which specific gene mutation causes nephrotic syndrome that is associated with thyroid changes. However, the most classic exam question framing of "thyroid-resistant nephrotic syndrome caused by mutation in gene encoding..." typically refers to the NPHS1 gene encoding nephrin (congenital nephrotic syndrome of Finnish type) or NPHS2 encoding podocin.
But re-reading the question carefully - "Thyroid resistant nephrotic syndrome" - this is most likely asking about resistance to thyroid hormone replacement seen in nephrotic syndrome because of urinary loss of thyroid hormone-binding proteins (TBG), OR it could refer to a specific genetic syndrome.
The most likely exam answer here is about NPHS2 (podocin) for steroid-resistant nephrotic syndrome, but the "thyroid" prefix is key. This is a well-known exam MCQ where the answer is that in nephrotic syndrome, TBG (thyroxine-binding globulin) is lost in urine, causing apparent thyroid resistance/hypothyroidism - and the specific gene question likely points to CUBN (cubilin) which causes a syndrome of proteinuria + thyroid abnormalities, or to the NPHS1/NPHS2 mutations.
Given the phrasing, this is almost certainly an exam MCQ asking about steroid-resistant nephrotic syndrome with the answer being either NPHS2 (podocin) or NPHS1 (nephrin).
Thyroid Resistant Nephrotic Syndrome - Gene Mutation
This question, as classically framed in medical examinations, has two possible interpretations - both important to know:
Interpretation 1: Steroid-Resistant Nephrotic Syndrome (SRNS)
The most common exam answer for steroid-resistant nephrotic syndrome caused by a single gene mutation:
| Gene | Protein Encoded | Inheritance | Syndrome |
|---|---|---|---|
| NPHS2 | Podocin | Autosomal recessive | Childhood-onset SRNS, FSGS |
| NPHS1 | Nephrin | Autosomal recessive | Congenital nephrotic syndrome of Finnish type |
| WT1 | Wilms tumor protein | AD/AR | Denys-Drash or Frasier syndrome |
| LAMB2 | Laminin-β2 | AR | Pierson syndrome |
-
NPHS2 (podocin) mutation is the most common genetic cause of steroid-resistant nephrotic syndrome in children. Podocin is an intracellular membrane-bound protein at the slit diaphragm of podocytes. Mutations impair nephrin-podocin interactions, leading to slit diaphragm dysfunction and massive proteinuria that does not respond to steroids.
- Brenner and Rector's The Kidney: "Nphs2, whose product is the intracellular membrane-bound protein podocin, is the first gene identified as being linked to steroid-resistant nephrotic syndrome (SRNS)."
- Robbins Pathology: "A distinctive pattern of autosomal recessive FSGS results from mutations in the NPHS2 gene, which encodes the intracellular slit diaphragm associated protein podocin. Mutations in NPHS2 are one cause of steroid-resistant nephrotic syndrome of childhood onset."
-
NPHS1 (nephrin) mutation causes congenital nephrotic syndrome of the Finnish type - massive proteinuria from birth, also steroid-resistant.
Interpretation 2: Thyroid Hormone Changes in Nephrotic Syndrome
In nephrotic syndrome, thyroid hormone-binding proteins are lost in the urine, including:
- Thyroxine-Binding Globulin (TBG) - main carrier (~75% of T4)
- Transthyretin (prealbumin)
- Albumin (binds ~15% of T4)
This results in low total T4 and T3 levels in plasma. Patients appear to have "thyroid resistance" - low hormone levels but typically remain euthyroid because free (unbound) hormone levels are normal. As Harrison's (22nd ed.) states: "Total thyroid hormone levels are... decreased when TBG binding is reduced (androgens, nephrotic syndrome)... unbound thyroid hormone levels are normal and the patient is euthyroid."
Most Likely Exam Answer
If the question asks "thyroid-resistant nephrotic syndrome caused by mutation in gene encoding ___", the expected answer is:
NPHS2 gene → encodes Podocin
This is the canonical genetic cause of steroid-resistant nephrotic syndrome (the word "thyroid" in the question is likely a typo or misdirection for "steroid"). Some exam questions specifically use this framing.
If it truly means thyroid-hormone resistance in the context of nephrotic syndrome, the mechanism involves urinary loss of TBG (encoded by the SERPINA7 gene), though this is secondary/acquired rather than a primary gene mutation causing the nephrotic syndrome itself.
Summary table:
| Question Intent | Gene | Protein |
|---|---|---|
| Steroid-resistant NS (most likely) | NPHS2 | Podocin |
| Congenital NS (Finnish type) | NPHS1 | Nephrin |
| TBG deficiency (thyroid binding loss) | SERPINA7 | TBG |
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