Reevaluation of a kindred with congenital absence of dermal ridges, syndactyly, and facial milia

Association between Mutation in SMARCAD1 and Basan Syndrome with Cutaneous Squamous Cell Carcinoma

Background

Basan syndrome is a rare autosomal-dominant ectodermal dysplasia with certain clinic-pathological features caused by mutations in the SMARCAD1 gene. Currently, no skin malignancy related to Basan syndrome has been reported. This study was aimed at identifying related gene mutations in a new Chinese pedigree with Basan syndrome and discovering the possible association between Basan syndrome and cutaneous squamous cell carcinoma (cSCC).

Methods

We report a case of Basan syndrome from China with family history of cSCC. The pedigree contains 28 individuals. Among them, 12 members had Basan syndrome, while 4 affected members were diagnosed with cSCC in the 1st and 2nd generations. Whole exome sequencing (WES) and Sanger sequencing were performed for 7 available individuals. The specific gene mutation on pre-mRNA splicing was also analyzed using in vitro Minigene assay. In addition, sequencing data was analyzed with bioinformatics workflow, aiming to discover the gene associated with cSCC.

Results

Gene sequencing results showed a heterozygous mutation, c.378+5G>A, in the SMARCAD1 gene in all tested individuals with Basan syndrome. Minigene result implicated the specific mutation may cause splicing variations by exon skipping occurring in the targeted exons.

Conclusion

To the best of our knowledge, this is the first study reported Basan syndrome with family history of cSCC. Despite in this study we cannot draw any conclusion about the association between Basan syndrome and cSCC at the genetic level, this study encourages future works to substantiate this potential but important issue.

Basan gets a new fingerprint: Mutations in the skin-specific isoform of SMARCAD1 cause ectodermal dysplasia syndromes with adermatoglyphia

Basan syndrome is an autosomal dominant ectodermal dysplasia (ED) with congenital adermatoglyphia, transient neonatal acral bullae, and congenital facial milia. Autosomal dominant adermatoglyphia (ADG) is characterized as adermatoglyphia with hypohidrosis. Recently mutations in the skin-specific isoform of the gene SMARCAD1 have been found in both syndromes. This report proposes to unify these two previously distinct ED, into one syndrome. We offer a new acronym: SMARCAD syndrome (SMARCAD1-associated congenital facial Milia, Adermatoglyphia, Reduced sweating, Contractures, Acral Bullae, and Dystrophy of nails). Sanger sequencing was performed on genomic DNA from a patient with Basan syndrome using primers designed to flank SMARCAD1. Sanger sequencing revealed a novel variant, NM_001254949.1:c.-10 + 2 T > G, in the donor splice site of exon 1 of the skin-specific isoform. This variant and the other five previously reported variants in Basan syndrome and ADG are all within the same donor splice site. We conclude that Basan syndrome and ADG are on a phenotypic spectrum of a monogenic syndrome which is better described by the acronym SMARCAD syndrome.

Heterozygous Deletion Impacting SMARCAD1 in the Original Kindred with Absent Dermatoglyphs and Associated Features (Baird, 1964)

In 1964, Baird described a family with adermatoglyphia, facial milia, and skin fragility. Using whole exome sequencing, genotyping, and Sanger sequencing, we identified a 116-kb heterozygous deletion involving exons 1-9 of SMARCAD1 in descendants of this kindred. This contrasts with point mutations within exon 9 in all other reported families.

Profuse congenital familial milia with absent dermatoglyphics (Basan's Syndrome): description of a new family

Milia are common, small, keratin-containing cysts frequently seen in all age groups. They may arise spontaneously or develop after a variety of stimuli. They can be found alone or as part of syndromes. We present a female neonate born not only with profuse facial milia, but also with acral bullae and absent dermatoglyphics. Similar features were seen in several members of her family. These findings correspond to the syndrome known as Basan's syndrome, a rare autosomal-dominant inherited dermatosis characterized by profuse congenital milia, transient neonatal acral bullae, and absence of dermatoglyphics.

Profuse congenital milia in a family

Milia are keratin containing dermal cysts and are seen very frequently in neonates. They generally resolve spontaneously within the first few months of life. However, the presence of congenital milia may also be associated with a number of inherited disorders. We present a family with congenital milia and no other associated abnormalities in whom the milia were profuse and more persistent than usual. A number of inherited disorders which may be associated with the presence of milia are also discussed.