Clinical Features and Mutation Analysis of the SMARCAD1 Gene in a Family with Basan Syndrome and a Literature Review / 罕见病研究

  Objective  To summarize the clinical features of a family with Basan syndrome and to analyze mutation of the SMARCAD1 gene.  Methods  The Basan family was diagnosed at Dermatology Hospital, Southern Medical University in 2022. Backgroud data was collected, and clinical and genetic characteristics were analyzed. Meanwhile, a retrospective analysis of features and associated genetic mutations reported in all patients with Basan syndrome was conducted.  Results  A total of 18 patients with Basan syndrome were identified, including 9 males and 9 females. All 18 patients had no fingerprints at birth (18/18, 100%), and some patients had knuckle pads, palmoplantar hyperkeratosis, nail atrophy, nail separation, and longitudinal nail ridges. Symptoms vary in severity. At the same time, it was found that c.-10+1G > T (as well as c.378+1G > T)mutations appeared on the intron 1 of the SMARCAD1 (NM_020159.5) gene in 7 patients, resulting in abnormal splicing.  Conclusions  This article provides help for the early diagnosis of Basan syndrome and helps to improve the diagnosis and differentiation level of clinicians.

Mosaic mutation in the NEMO gene causes incontinentia pigmenti in a male patient / 中华皮肤科杂志

Objective To identify mutations in the NEMO gene in a family with incontinentia pigmenti.Methods Clinical data were collected from the proband,and peripheral blood samples were obtained from the proband,her parents and 200 healthy controls.Multiplex PCR was performed to detect heterozygous deletion of exons 4-10 of the NEMO gene in the blood samples of the proband and her parents.Then,PCR was performed to amplify exons 2,3-10 of the NEMO gene in all the blood samples,and all exons in the gene coding region and their flanking sequences were subjected to DNA sequencing.DNA was extracted from paraffin-embedded lesional tissue of the proband's father,and PCR was performed to amplify exon 10 of the NEMO gene and its flanking sequence followed by DNA sequencing.Results The deletion of exons 4-10 of the NEMO gene was undetected in the peripheral blood of the proband or her father.Sanger sequencing showed that there was a heterozygous mutation c.1236dupA in exon 10 of the NEMO gene in the peripheral blood of the proband,which led to a mutation in amino acid residues (p.H413fs*7).The c.1236dupA mutation was not found in the peripheral blood of the proband's parents,while a mosaic mutation c.1236dupA was detected in the DNA from lesional tissues of the proband's father.Conclusion The mutation c.1236dupA in the NEMO gene may be the underlying cause of incontinentia pigmenti in the proband and her father.

Mutation analysis of the ABCA12 gene in two families with autosomal recessive congenital ichthyosis / 中华皮肤科杂志

Objective To detect mutations of the ABCA12 gene in 2 Chinese families with autosomal recessive congenital ichthyosis (ARCI).Methods According to the typical clinical manifestations,two probands were diagnosed with ARCI.DNA was extracted from the peripheral blood samples collected from the patients and their parents.High-throughput sequencing was conducted by using multi-gene array for genetic skin disorders to determine mutation sites in the probands,and then DNA isolated from the probands and their parents were bidirectionally verified by Sanger sequencing.Results Two compound heterozygous mutations (c.2759A＞G and c.7004A＞G) in the ABCA12 gene were found in the proband 1,and another two compound heterozygous mutations (c.6163_6164insT and c.7406G＞A) were identified in the proband 2.The parents of the two probands were heterozygous carriers of one of the two mutations in the ABCA12 gene.Function prediction for the 4 mutations showed that all of the 3 missense mutations (c.2759A＞G,c.7004A＞G and c.7406G＞A) may exert pathogenic effect,and fragnin encoded by the frameshift mutation c.6163_6164insT may also affect protein function,c.2759A＞G and c.6163_6164insT were newly identified mutation sites.Conclusion The compound heterozygous mutations in the ABCA 12 gene are the causative mutations responsible for ARCI in the two probands of the two pedigrees.

A case of tuberous sclerosis induced by a somatic mosaic mutation in the TSC2 gene / 中华皮肤科杂志

Objective To investigate clinical features and detect mutations in a case of tuberous sclerosis complex (TSC) caused by a somatic mosaic mutation in the TSC2 gene.Methods Peripheral blood samples were obtained from a patient with suspected TSC,his parents,and 200 unrelated healthy controls.Genomic DNA was extracted from these blood samples,polymerase chain reaction (PCR)and nextgeneration sequencing were performed to amplify all the exons and their flanking sequences of the TSC 1 and TSC2 genes followed by DNA sequencing,so as to identify mutations in the TSC 1 and TSC2 genes.DNA was also extracted from lesional skin tissues of the patient,and PCR was conducted to amplify the target fragment of the TSC2 gene followed by DNA sequencing.Results The patient clinically presented with facial angiofibroma,depigmented patches on the waist,periungual fibroma and angioleio-myolipoma of the kidney,which were consistent with the diagnosis of TSC.A mutation c.5130_5131insT(p.V1711Cfs* 18) was identified in the TSC2 gene in the patient.A higher frequency of the mutation was found in the DNA of the tumor tissue than in that of the peripheral blood.No such a mutation was found in his parents'DNA,unrelated healthy controls or any public database.Conclusion The somatic mosaic mutation c.5130_513 1insT in the TSC2 gene is responsible for the phenotype of TSC in the patient.

A case of X-linked ichthyosis complicated by Mal de Meleda: clinical features and mutation analysis of the SLURP-1 and STS genes / 中华皮肤科杂志

Objective To report a case of X-linked ichthyosis complicated by Mal de Meleda,and to identify the gene mutations.Methods Clinical data were collected from the patient,and peripheral blood samples were obtained from the patient,his parents and 100 unrelated healthy people who served as controls.Genomic DNA was extracted from these blood samples,and PCR was performed to amplify all the exons and their flanking sequences of the SLURP-1 and STS genes.All the amplification products were analyzed by agarose gel electrophoresis,and amplification products of the SLURP-1 gene were analyzed by DNA sequencing.Results The patient presented with regularly-arranged polygonal brown or black scales all over the trunk and limbs,erythematous hyperkeratotic lesions on the palms and soles,elbows and knees,inguinal and perianal regions,which extended to the dorsa of the hands and feet.Then,the patient was diagnosed with X-linked ichthyosis complicated by Mal de Meleda.Genetic testing showed complete deletion of the STS gene,and a homozygous mutation (c.286C ＞ T) at position 286 in exon 3 of the SLURP-1 gene,which led to the formation of a premature termination codon at amino acid position 96 (p.R96*).His parents were heterozygous carriers of the mutation (c.286C ＞ T).No mutation was found in the unrelated healthy controls.Conclusion The complete deletion of the STS gene and the homozygous nonsense mutation in the SLURP-1 gene may be the reason for X-linked ichthyosis complicated by Mal de Meleda in the patient.

Mutation analysis of the COL7A1 gene and prenatal diagnosis in two families with recessive dystrophic epidermolysis bullosa / 中华皮肤科杂志

Objective To detect mutations of the COL7A1 gene in 2 families with recessive dystrophic epidermolysis bullosa (RDEB),and to perform prenatal diagnosis during the pregnancy of patients' mothers.Methods Clinical data were collected from 2 patients with RDEB.DNA was extracted from the peripheral blood samples from the patients,their parents and 100 unrelated healthy people who served as controls.PCR was performed to amplify all the 118 exons of the COL7A1 gene followed by DNA sequencing.After identification of pathogenic mutations,amniotic fluid cells were obtained by amniocentesis during the next pregnancy of the patients' mothers,and genomic DNA was extracted from uncultured or cultured amniotic fluid cells followed by amplification and DNA sequencing to detect mutations in the COL7A1 gene.The results were compared with patients' results for prenatal diagnosis.After delivery,venous blood samples were collected from the neonates to detect mutations in the COL7A1 gene.All the results were verified by bidirectional sequencing.Results Compound heterozygous mutations in the COL7A1 gene were identified in the 2 patients.Two heterozygous mutations (c.5453G ＞ A and c.6781C ＞ T) in the COL7A1 gene were found in case 1,which resulted in the p.G1818D mutation and the formation of a premature termination codon p.R2261Efs*25.Additionally,the c.5453G ＞ A and c.6781C ＞T mutations were inherited from his father and mother respectively.Another 2 heterozygous mutations (c.6205C ＞ T and c.8272_8272delG) in the COL7A1 gene were identified in case 2,which led to the p.R2069C and p.V2758Sfs*28 mutations in encoded proteins,and the c.6205C ＞ T and c.8272_8272delG mutations were inherited from the patient's father and mother respectively.None of the above mutations in the COL7A1 gene was found in the uncultured or cultured amniotic fluid cells,which were collected from the 2 patients' mothers during the next pregnancy.After birth,the neonates showed normal skin and mucosa without blisters,and genetic testing showed none of the above mutations in the COL7A1 gene in the neonates.Conclusion Compound heterozygous mutations in the COL7A1 gene were found in the 2 patients with RDEB,and prenatal diagnosis was successfully performed in the 2 patients' mothers during the next pregnancy.

Mutation analysis of the SERPINB7 gene in two patients with Nagashima-type palmoplantar keratoderma / 中华皮肤科杂志

Objective To report two cases of Nagashima-type palmoplantar keratoderma(NPPK), and to identify mutations in the SERPINB7 gene. Methods Clinical data were collected from two patients with NPPK and their parents, and peripheral blood samples were obtained from the two patients, their parents and 200 unrelated healthy controls. Genomic DNA was extracted from these blood samples. PCR was performed to amplify 8 exons and their flanking sequences of the SERPINB7 gene followed by DNA sequencing. Results A homozygous mutation (c.796C > T), which led to the formation of a premature termination codon at amino acid position 266 (p.R266*), was identified in both of the two patients. However, the patients′ healthy parents were heterozygous carriers of the mutation(c.796C > T). No mutation was found in the unrelated healthy controls. Conclusion The mutation c.796C > T in the SERPINB7 gene may be responsible for NPPK in the two patients.

Diffuse cutaneous mastocytosis: a case report and mutation analysis of the KIT gene / 中华皮肤科杂志

Objective To analyze KIT gene mutations in one patient with diffuse cutaneous mastocytosis (DCM),and to provide a basis for the prediction of prognosis and selection of treatment.Methods Clinical data were collected from a boy with DCM.Peripheral blood samples were obtained from the patient,his parents and 200 unrelated healthy human controls.PCR was performed to amplify 21 coding exons and their flanking sequences of the KIT gene followed by DNA sequencing.Results A heterozygous missense mutation (c.1526A ＞ T),which leads to the mutation p.Lys509Ile,was detected in the KIT gene of the patient,but not in his parents or the healthy controls.Conclusion The heterozygous missense mutation p.Lys509Ile in the KIT gene may be a cause of DCM.

Mutation analysis of the ALDH3A2 gene in patients with Sj(o)gren-Larsson syndrome / 中华皮肤科杂志

Objective To assess mutations in the ALDH3A2 gene in two patients with Sj(o)gren-Larsson syndrome manifesting primarily as congenital ichthyosis,mental retardation and spastic paraplegia.Methods Two patients,a 2-year-old girl and a 1.5-year-old boy,with Sj(o)gren-Larsson syndrome were included in this study.None of their family members suffered from this disease.Peripheral blood samples were collected from the two patients,their family members (an elder brother and both parents),and 100 unrelated healthy controls.DNA was extracted from the blood samples,and subjected to PCR for the amplification of 10 encoding exons and their flanking sequences of the ALDH3A2 gene followed by DNA sequencing.Results A homozygous missense mutation c.325G ＞ A,which leads to the substitution of glycine by arginine at position 109,was detected in the ALDH3A2 gene of patient 1,whose parents and elder brother were heterozygous carriers of this mutation.The patient 2 carried compound heterozygous mutations,including c.1157A ＞ G (p.Asn386Ser) inherited from his father and c.1294A ＞ T (p.Arg432X) inherited from his mother.None of these mutations was detected in the unrelated healthy controls.Conclusion The homozygous mutation p.Gly109Arg and compound heterozygous mutations p.Asn386Ser and p.Arg432X present in these patients may be associated with clinical phenotypes of Sj(o)grenLarsson syndrome.

Analysis of COL7A1 gene mutations in a family with recessive dystrophic epidermolysis bullosa inversa / 中华皮肤科杂志

Objective To observe the ultrastructural features of recessive dystrophic epidermolysis bullosa inversa(RDEB-Ⅰ)and to detect the mutations of COL7A1 gene in a family with RDEB-Ⅰ.Methods A 24-year-old male patient complained of recurrent vesicles in the skin for 24 years.The lesions began as generalized pruritic vesicles and bullae soon after birth,with a predilection for areas subject to friction,and showed a trend to be worse in summer but mild in winter.No photosensitivity was observed.When he was 3 to 4 years old,the lesions were decreased in number,with the only involvement of the trunk and abdomen;thereafter,the lesions were improved year by year.The patient suffered from nephritis at the age of 5 years,which progressed into renal failure at the age of 15 years.He received renal transplantation and was given long-term oral tacrolimus and mycophenolate mofetil,which leaded to an improvement in the lesions.The family history was unremarkable,and the marriage between her parents was not consanguineous.Dermatological examination revealed large areas of irregularly-marginated,hypopigmented,atrophic scar on the waist,back and abdomen with onychodystrophy involving multiple nails.No vesicles were observed.Immunofluorescence antigen mapping and transmission electron microscopy were conducted to observe the expression of type Ⅶ collagen in and ultrastructure of cutaneous lesions from the patient.Venous blood samples were obtained from the patient as well as his parents and 3 sisters,and drill biopsy specimens were obtained from the margin of vesicular lesions and unaffected anterior tibial skin of the patient.DNA specimens were obtained from the blood samples of the family members and 150 unrelated healthy controls,and RNA was extracted from the biopsy samples of the patient.PCR and direct sequencing were carried out to detect mutations in COL7A1 gene,and reverse transcription-PCR was conducted to confirm the mutation at mRNA level.Results Skin cleavage was observed under lamina densa in the dermis,with a decrease in anchoring fibrils and expression of type Ⅶ collagen in the lesions of the patient.A heterozygous synonymous mutation c.C5499T which created a new splicing site and leaded to a premature terminal codon,as well as a heterozygous missense mutation c.C6205T(C-T transition at codon 2069:CGT to TGT)which leaded to the substitution of arginine by cysteine,were identified in the COL7A1 gene of the proband and all of his sisters,but not in any of the unrelated controls.The c.C5499T and c.C6205T mutations were inherited from the patient's father and mother respectively.Conclusion The compound heterozygous mutations c.C6205T and c.C5499T may be responsible for RDEB-Ⅰ in this patient.

Mutation analysis of CARD15/NOD2 gene in a patient with early-onset sarcoidosis / 中华皮肤科杂志

Objective To detect the mutation of CARD15 gene in a patient with sarcoidosis and tuberculosis.Methods Clinical data were collected from a 32-year-old male patient with early-onset sarcoidosis and tuberculosis.Peripheral blood was obtained from the patient,both of his parents,and 102 healthy controls.All the 12 exons of the coding regions as well as flanking intronic sequences of the CARD15 gene were amplified by PCR followed by direct sequencing.The resulted sequences were blasted against the reference sequences of CARD15 gene.Results Both clinical features and histopathological findings of the patient were consistent with sarcoidosis.Furthermore,the patient presented with flexion contractures of fingers and toes,as well as iridocyclitis.A heterozygous missense recurrent mutation c.1000C ＞ T (p.R334W) was detected in exon 4 of the CARD15 gene in the patient,but not in either of his parents or any of the 102 healthy controls.Conclusions A p.R334W mutation in the CARD15 is identified in the patient,which may be responsible for the clinical phenotype of earlyonset sarcoidosis.Gene analysis may be a useful method to clarify the etiology of early-onset sarcoidosis.

Mutations of COL7A1 gene in three cases of dystrophic epidermolysis bullosa pruriginosa / 中华皮肤科杂志

Objective To detect the mutations of COL7A1 gene in three cases of dystrophic epidermolysis bullosa pruriginosa (DEBP). Methods Clinical data were collected from 3 patients with DEBP. Skin lesions were obtained from these patients and subjected to transmission electron microscopy. DNA was extracted from the peripheral blood of the 3 patients, their 16 relatives, and 150 unrelated normal human controls, and PCR was performed to amplify all the exons and flanking sequences of COL7A1 gene followed by sequencing.Results The patient 1 and 2 had family history, whereas the case 3 was sporadic. Transmission electron microscopy showed tissue cleavage beneath lamina densa in case 1 and slightly decreased anchoring fibrils in some areas of the lesions in case 1 and 3. Three heterozygous mutations of COL7A1 gene, i.e., c. G6734T, c.G6859A and c. G5318T, which leaded to three amino acid mutations, i.e., p. G2245V, p. G1773V and p. G2287R, were found in patient 1, 2 and 3 respectively. Of them, p. G2245V and p. G1773V were novel mutations. The mutations strictly cosegregated with the phenotype in the patients of family 1 and 2. No mutation was detected in the unaffected parents of patient 3 or the 150 unrelated healthy controls. Conclusions The p. G2245V, p. G2287Rand p. G1773V mutations of COL7A1 gene may be responsible for the phenotype of DEBP in the three cases,and of them, p. G2245V and p. G1773V have never been reported.

Ultrastructure of skin lesions and mutations in the FERMT1 gene in a patient with Kindler syndrome / 中华皮肤科杂志

Objective To study cutaneous ultrastructural changes and FERMT1 gene mutations in a patient with Kindler syndrome. Methods Clinical data were collected, and tissue samples obtained from the lesions of poikiloderma were observed by using transmission electron microscopy. Fifteen coding exons and their flanking sequences of the FERMT1 gene were amplified by PCR and DNA sequencing was followed.Results Reduplication of lamina densa was seen between the dermal-epidermal junctions of the lesional skin. The patient was found to be homozygous for a novel splice-site mutation (IVS9 + 1G ＞ A) in FERMT1 gene, and his parents were heterozygous for it. The mutation was undetected in fifty normal control individuals.Conclusions Transmission electron microscopy may serve as an ancillary examination for the diagnosis of Kindler syndrome. The IVS9+1G＞A mutation of FERMT1 gene may contribute to the clinical phenotype of Kindler syndrome in this patient.