case_images: PMC10850558_01
case_images: PMC10850558_02
case_images: OGTT and HOMA-IR results pre- and post-treatment. Blood glucose (A), C-peptide (B), and insulin levels (C) are charted at various intervals post-sugar intake, both prior to and following treatment. The patient's HOMA-IR before and after treatment is presented in (D).
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case_images: PMC10850558_02_fendo-14-1327729-g001.jpg
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case_images: In order to gain further insights into the patient's blood glucose profile, an OGTT was administered ( Figures 1A-C ). Figure 1D ), signifying a notable degree of insulin resistance. For comparative analysis, we collected data from 46 GS patients in our department, including 30 males (65.2%) and 16 females (34.8%), with an average age of 34.7 +- 13.6 (Q1-Q3: 24.2-43.0) years old, BMI of 25.1 +- 3.6 kg/m2 (Q1-Q3: 22.3-27.5), blood potassium levels of 2.8 +- 0.4 mmol/L (Q1-Q3: 2.6-3.1), blood magnesium levels of 0.6 +- 0.2 mmol/L (Q1-Q3: 0.5-0.8), HbA1c levels of 5.6 +- 0.8% (Q1-Q3: 5.2-5.9) ( Figure 2A ), fasting insulin of 12.4 +- 7.0 mu/L (Q1-Q3: 6.7-17.0) ( Figure 2B ) and HOMA-IR of 2.8 +- 1.7 (Q1-Q3: 1.6-4.1) ( Figure 2C ). Interestingly, a significant improvement was observed when Metformin was discontinued for a week before re-administering the OGTT (as detailed in  Figures 1A-C ). The subsequent assessment unveiled a marked reduction in insulin resistance, highlighted by a HOMA-IR score of 5.45 ( Figure 1D ).
case_images: Distribution of HbA1c levels (A), fasting insulin (B) and HOMA-IR (C) among GS patients from our department. The arrows indicate the specific value for the highlighted patient.
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case_images: PMC10850558_02_fendo-14-1327729-g002.jpg
case_images: f2
case_images: Figure 1D ), signifying a notable degree of insulin resistance. For comparative analysis, we collected data from 46 GS patients in our department, including 30 males (65.2%) and 16 females (34.8%), with an average age of 34.7 +- 13.6 (Q1-Q3: 24.2-43.0) years old, BMI of 25.1 +- 3.6 kg/m2 (Q1-Q3: 22.3-27.5), blood potassium levels of 2.8 +- 0.4 mmol/L (Q1-Q3: 2.6-3.1), blood magnesium levels of 0.6 +- 0.2 mmol/L (Q1-Q3: 0.5-0.8), HbA1c levels of 5.6 +- 0.8% (Q1-Q3: 5.2-5.9) ( Figure 2A ), fasting insulin of 12.4 +- 7.0 mu/L (Q1-Q3: 6.7-17.0) ( Figure 2B ) and HOMA-IR of 2.8 +- 1.7 (Q1-Q3: 1.6-4.1) ( Figure 2C ).
case_images: SLC12A3 and PDX1 mutations: localization, 3D structure, and DNA sequencing analysis. (A) Localization of SLC12A3 mutations on the NCC protein structure. The diagram shows the intracellular amino- and carboxy-terminal domains, along with transmembrane domains 1 to 12. The SLC12A3 mutation sites are indicated, with mutations from left to right being p.Ala226Thr, p.Ala370Pro, and p.Gly800Arg. (B) The predictive three-dimensional structures of the NCCT with missense mutations. From left to right, the diagrams depict the three-dimensional structures of the NCC with p.Ala226Thr, p.Ala370Pro, and p.Gly800Arg mutations. The mutation sites are highlighted within a black box, magnified and presented in a spherical bar chart format. (C) DNA sequence analysis of SLC12A3 and PDX1 missense mutations identified in the patient. Arrows indicate heterozygous nucleotide substitutions. Sequencing at the 1108th base of the 9th exon of SLC12A3 revealed a G-to-C substitution, resulting in an amino acid substitution from Ala to Pro at position 370. Sequencing at the 676th base of the 5th exon of SLC12A3 showed a G-to-A substitution, leading to an amino acid substitution from Ala to Thr at position 226. Sequencing at the 2398th base of the 20th exon of SLC12A3 demonstrated a G-to-A substitution, causing an amino acid substitution from Gly to Arg at position 800. Sequencing at the 97th base of the 1st exon of PDX1 indicated a C-to-G substitution, resulting in an amino acid substitution from Pro to Ala at position 33.
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case_images: PMC10850558_02_fendo-14-1327729-g003.jpg
case_images: f3
case_images: The detailed mutation site distribution map of the NCC is presented in  Figure 3A , and the predictive three-dimensional structural diagrams for the missense mutations are displayed in  Figure 3B . The p.Ala370Pro mutation is located in the transmembrane region of NCC, while the other two mutation sites are in the intracellular segment of the protein.  Figure 3C  presents the DNA sequence analysis of SLC12A3, showing the specific nucleotide substitutions and resulting amino acid changes. Adding another layer of complexity, the patient also harbored a mutation in the PDX1 gene: c.97C>G in exon 1 ( Figure 3C ).
case_images: Family pedigree of the patient. Affected individuals are represented by solid symbols. The arrow indicates the patient.
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case_images: Sanger sequencing-based family verification revealed the inheritance pattern of these mutations: the SLC12A3 c.676G>A mutation was maternally inherited, while the remaining two were paternally derived (depicted in  Figure 4 ). Furthermore, the patient transmitted both the SLC12A3 c.676G>A and PDX1 c.97C>G mutations to his two daughters (as shown in  Figure 4 ), neither of whom currently manifest hypokalemia or abnormal glucose tolerance.