Pedigree analysis and clinical data of familial benign chronic pemphigus
Pedigree analysis and clinical data of pedigree Ⅰ
Among 4 generations of the pedigree, there are 2 HHD patients (1 male and 1 female) who were present in the 2nd and 3rd generations, consistent with the inheritance pattern of autosomal dominant genetic disease (Figure 1A). The proband is a 50 year-old woman whose parents were not biological related. Physical exam showed that she had good health condition in general, and no abnormality was found in other body systems. Clinical manifestations included erythema, blisters, erosions under bilateral axilla, left groin and umbilicus, and slight hypertrophy of skin in the left groin (Figure 1B). Histopathological examination of typical skin lesions in the left groin revealed cracks in the epidermis and partial loss of the stratum corneum. The spines in the lower and middle layers of epidermis were loosened and cells of spinous layer were visible (Figure 1C).
Pedigree analysis and clinical data of family Ⅱ
Among 3 generations of the pedigree, there were 3 patients, one male and two females. The patients were present in two consecutive generations Ⅱ and Ⅲ, consistent with the inheritance pattern of autosomal dominant genetic disease (Figure 1D). The proband was a 43 year-old male whose parents were not blood related. Physical exam showed that he had good general health condition without abnormality found in other body system. Clinical manifestations included flaky erythematous papule under the left armpit and left groin, perianal area, left popliteal fossa, adjacent popliteal fossa, obvious erosion in addition to some erythema (Figure 1E). The left axillary skin lesions were taken for pathological examination. The results showed that the spines in the lower and middle layers of epidermis were loosened, and were overflowed on the top with red blood cells. A single layer of basal cells covered on the dermal papilla and formed a villi (Figure 1F).
Clinical data of sporadic case I
Among 3 generations of the pedigree, there was only 1 patient. No other patients in the pedigree were seen. No obvious sign of familial genetic disease was observed. The patient was a 68 year-old male whose parents were not blood related. Physical exam showed that this patient was generally in a good health condition without obviously abnormalities found in other body systems. Clinical manifestations included erythema on both sides of the groin and anus, scattered papules in addition to the anal erythema, obvious erosion and exudation in the skin lesions (Figure 2A). A piece of skin from lesions on the left groin was taken for histological exam. The results showed that spines in the middle and lower layers of the epidermis were loosen and formed fissures in which loosening cells were presented (Figure 2B).
Clinical data of sporadic cases Ⅱ
Among 3 generations of the pedigree, there was 1 patient only. No other patients in the
pedigree were seen. No obvious inheritance pattern of familial genetic diseases was shown. The patient was a 42 years old male whose parents were not blood related. Physical exam showed that this patient had good general health condition without other abnormalities found in other body systems. Clinical manifestations included slight erythema and desquamation on the back of right ear, erythematous papular rash on both sides of the groin, obvious erosion and exudation in addition to some erythema, and epidermal lesions on the left groin covered with crust (Figure 2C). Histopathological examination of the typical skin lesions from the left groin showed that the spinal layer in the epidermis formed fissures in which the loosening cells were scattered around (Figure 2D).
Gene sequencing of ATP2C1
PCR amplification for the exons of ATP2C1
Exon 26 of ATP2C1 in pedigree Ⅰ, exon 15 of ATP2C1 in pedigree Ⅱ, exon 8 of ATP2C1 in sporadic patient I, and exon 22 of ATP2C1 in sporadic patient Ⅱ were amplified (Figure 3A). The sizes of PCR products were 312 bp, 383 bp, 425 bp and 298 bp respectively.
The sequencing result of exon 26 of ATP2C1 in pedigree I
A synonymous mutation c.G2598A in exon 26 was found in the proband of pedigree Ⅰ, which was further confirmed by reverse sequencing that showed a complementary nucleotide mutation. The mutation did not change amino acid code of lysine. We further verified this mutation was actually a nonsense mutation that was not previously reported (Figure 3B). Such mutation was not found in the normal members of this pedigree or other people who were not blood related (Figure 3C, D, E).
Sequencing results of ATP2C1 exon 15 in pedigree Ⅱ
A missense mutation c.C1286A was detected in the exon 15 of the proband in pedigree Ⅱ, which was further confirmed by reverse sequencing that showed a complementary nucleotide mutation. This mutation changed the original alanine to aspartic acid (p.A429D). We further verified that it was actually an unreported missense mutation (Figure 4A-D). Such mutation was not found in the normal members of this pedigree or other people who were not blood related (Figure 4B, C).
Sequencing results of ATP2C1 exon 8 in sporadic case Ⅰ
A nonsense mutation c.C635A in exon 8 was detected in the proband of sporadic case I. This mutation was further confirmed by reverse sequencing that showed a complementary nucleotide mutation. This mutation resulted in a premature stop codon in the polypeptide chain and was previously reported (Figures 5A-D). Such mutation was not seen in the normal human controls (Figure 5B, C).
Sequencing results of ATP2C1 exon 22 in sporadic case II
A missense mutation c. A1931G was detected in exon 22 of the proband in sporadic case Ⅱ, which was further confirmed by reverse sequencing that showed a complementary nucleotide mutation. This mutation changed the original 644th aspartic acid (GAU) to be Glycine (GGU) (p. D644G). We noticed that this mutation was previously reported (Figure 6A-D). Such mutation in the gene was not found in the normal members in the pedigree and other people who were not blood related (Figure 6B, C).
IHC staining for hSPCA1
hSPCA1 is mainly expressed in the cytoplasm of keratinocytes in the epidermal layer with some on the cell membrane. Positive staining appeared as yellow or tan particles or clumps. In normal human skin tissues (Figure 7A-a), hSPCA1showed strong positive signals, that is, a dark brown stained band in the epidermis. The negative control in which the hSPCA1 antibody was replaced with PBS (Figure 7A-a, right corner inset) did not show any nonspecific staining. The expression levels of hSPCA1 in the skin tissues of all patients with HHD (Figure 7A-b/c/d, E) were significantly lower than that of the positive control, especially at the typical skin lesions (acanthosis). No obvious staining signal was seen even in some local areas (Figure. 7A-c).
IHC staining for proteins in relevant signaling pathways
IHC for p63
P63 is an intranuclear protein and can be stained in the nucleus of keratinocytes in the epidermal layer. In normal human skin tissues, p63 staining was strongly positive in the nucleus. In the area adjacent to the stratum corneum the nucleus gradually disappeared with differentiation, therefore, the staining is mainly present in the basal layer (Figure 7B-a). PBS was used as a negative control, which did not show any non-specific staining (Figure 7B-a, right corner inset). The expression level of p63 protein in the nucleus of HHD patients was significantly reduced compared to the positive control, especially in the typical lesions (Figure 7B-b/c/d, E). No obvious staining was seen in some local areas of the tissue.
IHC for Notch1
Notch1 is expressed in the cytoplasm of keratinocytes in the epidermal layer. In normal human skin tissues, Notch1 was strongly stained, appeared as brown or tan particles or clumps (Figure 7C-a). In the entire epidermal layer, Notch1 showed a even deep-stained band. In the skin tissues of all HHD patients, Notch1 signals (Figure7C-b/c/d, E) were weaker compared to the positive control. In contrast, the negative control by using PBS instead of Notch1 antibody did not show any non-specific staining (Figure 7C-a, right corner inset).
IHC for HKⅡ protein
HKⅡ is expressed in the cytoplasm of the keratinocytes in the epidermal layer. In normal human skin tissues, HKⅡ was strongly stained (Figure 7D-a) and showed a even deep-stained band in the entire epidermal layer. In contrast, the expression level of HKⅡ in the cytoplasm of skin lesion tissues was significantly reduced compared to the normal human positive control (Figure 7D-b/c/d, E). The negative control by using PBS other than HKⅡ antibody (Figure 7D-a, right corner inset) did not show obviously non-specific staining.
Real time PCR for miR-203
RNA was extracted from the skin lesion tissues of HHD patients and real-time PCR was performed to detect the expression level of miR-203 in these tissues. Normal human skin tissue was used as a control. The data showed that the levels of miR-203 in the skin lesions of HHD patients were significantly upregulated compared to that in the normal human control (Figure 8).