Hair bulb and two sebaceous glands [32?34]. Nontylotrich or secondary hair follicles (SHFs) begin to differentiate at approximately E16 [33]. In order to assess whether PHFs or SHFs or both are affected in the mutant mice, we intercrossed pigskin mice with a BMP4-lacZ reporter strain (from Dr. Yas Fututa) [24]. These mice have a lacZ reporter inserted into the endogenous BMP4 locus by homologous recombination [24]. BMP4 expression is robust at the onset of primary and secondary hair follicle induction [35,36]. Interestingly, at E14.5, the pigskin mutants showed a similar pattern, distribution and density 15900046 of PHFs compared to the control (Fig. 6A). There were no significant changes of PHFs inhibitor numbers in the control and mutant mice (the numbers per square millimeter: wt = 23.562.1, pigskin = 24.663.2, n = 3, p = 0.57). However, at E16.5, skin from the pigskin mutants showed a significant decrease in the numbers of hair follicles compared to the control littermates (Fig. 6B). Notably, the ratio of SHFs to PHFs in the mutant epidermis is significantly decreased (the ratio of SHFs to PHFs: wt = 3.0160.20, pigskin = 1.2760.28, n = 3, p,0.01). Thus, the Fatp4 mutation leads to a reduction of number of SHFs. Skin barrier formation follows a precise spatiotemporal pattern during embryogenesis [37]. The timing of development of the epidermal barrier can be examined by incubation of embryos in X-Gal solution at low pH. Detection endogenous 
beta-galactosidase activity occurs only prior to development of the barrier. Using this approach, previous studies demonstrated that Fatp4 mutant skin has a barrier defect at E18.5 and in newborn mice [9,10,12]. In our study, when we performed X-gal staining to detect the BMP4-LacZ activity in hair follicles, we found that X-gal penetrated the epidermis and stained the hair follicles 
in both control and mutant embryos at E14.5 (Fig 6.A). However, interestingly, at E15.5, blue staining was almost completely absent from the dorsal skin of the mutant embryos, but was observed throughout the dorsum of the control littermates (Fig. 6C). BlueA New Mouse Model for Congenital IchthyosisScandinavia, Middle East and North Africa [11]. IPS is more prevalent in Norway and Sweden with an estimated local carrier frequency of one in 50 suggesting a founder mutation. Outside of this region, only 23727046 a few cases have been reported in other inhibitor countries including Germany, Finland, Italy, Denmark and France. All patients from this region were found homozygous or compound heterozygous for p.C168X nonsense mutation. Up to now, thirteen distinct FATP4 mutations have been found in IPS patients (see summary in Figure 5A), including two nonsense mutations, eight missense mutations, one start site mutation, and two splice site mutations [11,28?1]. Notably, all of patients with IPS were reported to present similar clinical features. In our case, a point mutation (an A to T transversion) in the consensus splice donor sequence at the 39-end of exon 9 results in exon skipping and predicts synthesis of a truncated protein without the FATP/ VLACS motif. The consensus genomic 59 splice sequence in mammals, from 23 to +6 relative to the exon/intron boundary, is 59-CAGGTAAGT. This sequence binds with perfect complementarity to the U1 snRNA. Although A is the nucleotide found most often at position 22 (64 of the time), T is present 14 of the time, so the presence of a T does not intrinsically prevent efficient splicing [43?5]. Looking specifically at intro.Hair bulb and two sebaceous glands [32?34]. Nontylotrich or secondary hair follicles (SHFs) begin to differentiate at approximately E16 [33]. In order to assess whether PHFs or SHFs or both are affected in the mutant mice, we intercrossed pigskin mice with a BMP4-lacZ reporter strain (from Dr. Yas Fututa) [24]. These mice have a lacZ reporter inserted into the endogenous BMP4 locus by homologous recombination [24]. BMP4 expression is robust at the onset of primary and secondary hair follicle induction [35,36]. Interestingly, at E14.5, the pigskin mutants showed a similar pattern, distribution and density 15900046 of PHFs compared to the control (Fig. 6A). There were no significant changes of PHFs numbers in the control and mutant mice (the numbers per square millimeter: wt = 23.562.1, pigskin = 24.663.2, n = 3, p = 0.57). However, at E16.5, skin from the pigskin mutants showed a significant decrease in the numbers of hair follicles compared to the control littermates (Fig. 6B). Notably, the ratio of SHFs to PHFs in the mutant epidermis is significantly decreased (the ratio of SHFs to PHFs: wt = 3.0160.20, pigskin = 1.2760.28, n = 3, p,0.01). Thus, the Fatp4 mutation leads to a reduction of number of SHFs. Skin barrier formation follows a precise spatiotemporal pattern during embryogenesis [37]. The timing of development of the epidermal barrier can be examined by incubation of embryos in X-Gal solution at low pH. Detection endogenous beta-galactosidase activity occurs only prior to development of the barrier. Using this approach, previous studies demonstrated that Fatp4 mutant skin has a barrier defect at E18.5 and in newborn mice [9,10,12]. In our study, when we performed X-gal staining to detect the BMP4-LacZ activity in hair follicles, we found that X-gal penetrated the epidermis and stained the hair follicles in both control and mutant embryos at E14.5 (Fig 6.A). However, interestingly, at E15.5, blue staining was almost completely absent from the dorsal skin of the mutant embryos, but was observed throughout the dorsum of the control littermates (Fig. 6C). BlueA New Mouse Model for Congenital IchthyosisScandinavia, Middle East and North Africa [11]. IPS is more prevalent in Norway and Sweden with an estimated local carrier frequency of one in 50 suggesting a founder mutation. Outside of this region, only 23727046 a few cases have been reported in other countries including Germany, Finland, Italy, Denmark and France. All patients from this region were found homozygous or compound heterozygous for p.C168X nonsense mutation. Up to now, thirteen distinct FATP4 mutations have been found in IPS patients (see summary in Figure 5A), including two nonsense mutations, eight missense mutations, one start site mutation, and two splice site mutations [11,28?1]. Notably, all of patients with IPS were reported to present similar clinical features. In our case, a point mutation (an A to T transversion) in the consensus splice donor sequence at the 39-end of exon 9 results in exon skipping and predicts synthesis of a truncated protein without the FATP/ VLACS motif. The consensus genomic 59 splice sequence in mammals, from 23 to +6 relative to the exon/intron boundary, is 59-CAGGTAAGT. This sequence binds with perfect complementarity to the U1 snRNA. Although A is the nucleotide found most often at position 22 (64 of the time), T is present 14 of the time, so the presence of a T does not intrinsically prevent efficient splicing [43?5]. Looking specifically at intro.
