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    1. Amounts of A2E in the eyes of Abca4PV/PV, Abca4−/− and WT mice at the ages of 1, 3, 6, 12 and 15 months were quantified by reverse-phase high-performance liquid chromatography (HPLC) (Fig. 9B). Mice were raised under a regular 12-h light (∼10 lux)/12-h dark cycle. Age-dependent A2E accumulation was noted in all genotypes, with Abca4PV/PV and Abca4−/− mice accumulating about 5-fold more A2E than WT mice. No statistically significant differences in A2E accumulation were found between Abca4PV/PV and Abca4−/− animals.

      Autofluorescence and A2E production was measured in transgenic mice and showed loss of function of ABCA4 protein indicating that this variant impacts protein function (PS3; PMIDs).

    1. Screening of reported pathogenic variants in ABCA4 for Stargardt (STGD) The disease prevalence of STGD is estimated as 1 in 10000 individuals4. It has been estimated that about 70% of STGD patients carry variants in ABCA45. Therefore, this represents the scenario of a recessive disease with a relatively homogeneous genetic cause. We screened 945 reported pathogenic variants in ABCA4 genes collected in HGMD. Among them, 11 variants are likely benign, as their population AF in is higher than 0.7% (1/20000‾‾‾‾‾‾‾‾√)<math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M11"><mrow><mrow><mo>(</mo><mrow><msqrt><mrow><mn>1</mn><mo>/</mo><mn>20000</mn></mrow></msqrt></mrow><mo>)</mo></mrow></mrow></math>, the cutoff based on STGD disease prevalence, therefore were excluded from further analysis. The remaining 934 variants were subjected to our test model. As a result, 26 variants with the AF in the range of 0.46% to 0.03% were identified as likely benign (Binomial test1, Bonferroni correction p-value ≤ 0.05/934 and test2 Bonferroni correction p-value > 0.05/934) (Figure 3A).

      This variant is reported in Table S6, but only location, predictions, frequencies, etc are reported for it, not cases.

    2. Screening of reported pathogenic variants in ABCA4 for Stargardt (STGD) The disease prevalence of STGD is estimated as 1 in 10000 individuals4. It has been estimated that about 70% of STGD patients carry variants in ABCA45. Therefore, this represents the scenario of a recessive disease with a relatively homogeneous genetic cause. We screened 945 reported pathogenic variants in ABCA4 genes collected in HGMD. Among them, 11 variants are likely benign, as their population AF in is higher than 0.7% (1/20000‾‾‾‾‾‾‾‾√)<math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M11"><mrow><mrow><mo>(</mo><mrow><msqrt><mrow><mn>1</mn><mo>/</mo><mn>20000</mn></mrow></msqrt></mrow><mo>)</mo></mrow></mrow></math>, the cutoff based on STGD disease prevalence, therefore were excluded from further analysis. The remaining 934 variants were subjected to our test model. As a result, 26 variants with the AF in the range of 0.46% to 0.03% were identified as likely benign (Binomial test1, Bonferroni correction p-value ≤ 0.05/934 and test2 Bonferroni correction p-value > 0.05/934) (Figure 3A).

      This variant is reported in Table S6, but only location, predictions, frequencies, etc are reported for it, not cases.

    1. (http://genetics.bwh.harvard.edu/pph2/). In addition, mutation taster predicted both L168F and L168S variant as disease-causing with PROVEAN predictions of L168F (-2.767) and L168S (-4.083) as deleterious (https://www.mutationtaster.org/). As such, it was not surprising that the L168S variant patient had much more severe disease onset and rapid progression compared to other SCA34-causing ELOVL4 variants. For example, a patient carrying the T233M ELOVL4 variant was reported to develop ataxia starting at 15 years of age [10]. However, at the time of examination of this patient at 60 years of age, an MRI of the brain showed only subtle flattening of the ventral pons and mild cerebellar atrophy [10]. Another patient carrying the Q180P ELOVL4 variant developed ataxia in his mid-20 s and showed cerebellar and pontine atrophy [11]. Japanese patients also carrying the W256G variant developed gait ataxia between 13–56 years of age [12]. However, disease progression was reported to be very slow, and patients did not require assistance with walking with a walker or cane until the age of 60 years or older [12]. Taken together, it looks like the nature of the mutation and its effect on normal ELOVL4 function most likely through defects in VLC-FA biosynthesis or conformational changes in protein structure are critical to disease onset and severity of the pathologies.

      SupplementalData: