Novel de novo missense mutation in the interferon regulatory factor 6 gene in an Italian infant with IRF6-related disorder

Background

Congenital maxillomandibular syngnathia is a rare craniofacial anomaly leading to difficulties in feeding, breathing and ability to thrive. The fusion may consist of soft tissue union (synechiae) to hard tissue union. Isolated cases of maxillomandibular fusion are extremely rare, it is most often syndromic in etiology.

Case presentation

Clinical management of a female newborn with oromaxillofacial abnormities (synechiae, cleft palate, craniofacial dysmorphisms, dental anomaly) and extraoral malformations (skinfold overlying the nails of both halluces, syndactyly, abnormal external genitalia) is presented. The associated malformations addressed to molecular genetic investigations revealing an interferon regulatory factor 6 (IRF6)-related disorder (van der Woude syndrome/popliteal pterygium syndrome). A novel de novo heterozygous mutation in exon 4 of IRF6 gene on chromosome 1q32.2, precisely c.262A > G (p.Asn88Asp), was found. Similarities are discussed with known asparagine missense mutations in the same codon, which may alter IRF6 gene function by reduced DNA-binding ability. A concomitant maternal Xp11.22 duplication involving two microRNA genes could contribute to possible epigenetic effects.

Conclusions

Our reported case carrying a novel mutation can contribute to expand understandings of molecular mechanisms underlying synechiae and orofacial clefting and to correct diagnosing of incomplete or overlapping features in IRF6-related disorders. Additional multidisciplinary evaluations to establish the phenotypical extent of the IRF6-related disorder and to address family counseling should not only be focused on the surgical corrections of syngnathia and cleft palate, but also involve comprehensive otolaryngologic, audiologic, logopedic, dental, orthopedic, urological and psychological evaluations.

Bartsocas-Papas syndrome: The first case report of severe autosomal recessive form from Indonesia

INTRODUCTION

Bartsocas-Papas syndrome (BPS) is an autosomal recessive form of Popliteal Pterygium syndrome (PPS). It is a very rare disease characterized by congenital craniofacial anomalies, popliteal webbing, and genitourinary and musculoskeletal anomalies. Almost all of the cases were reported in dead intrauterine pregnancies.

PRESENTATION OF CASE

We present a 10-month-old boy with bilateral complete cleft lip and palate, abnormal scalp hair, an absence of both upper eyelids, choanal atresia, syndactyly of the third and fourth fingers of the right hand, agenesis fingers on the left hand, bilateral popliteal pterygia, bilateral talipes equinovarus, agenesis of the toes of both lower extremities, intercrural webbing, an absence of testis, and scrotal anomaly. Multistage surgical correction was performed for the multiple congenital malformations.

CONCLUSION

We report the first case of BPS from Indonesia. Gradual management should be performed according to the patient's age and available facilities.

Non-random distribution of deleterious mutations in the DNA and protein-binding domains of IRF6 are associated with Van Der Woude syndrome

BACKGROUND

The development of the face occurs during the early days of intrauterine life by the formation of facial processes from the first Pharyngeal arch. Derangement in these well-organized fusion events results in Orofacial clefts (OFC). Van der Woude syndrome (VWS) is one of the most common causes of syndromic cleft lip and/or palate accounting for 2% of all cases. Mutations in the IRF6 gene account for 70% of cases with the majority of these mutations located in the DNA-binding (exon 3, 4) or protein-binding domains (exon 7-9). The current study was designed to update the list of IRF6 variants reported for VWS by compiling all the published mutations from 2013 to date as well as including the previously unreported VWS cases from Africa and Puerto Rico.

METHODS

We used PubMed with the search terms; "Van der Woude syndrome," "Popliteal pterygium syndrome," "IRF6," and "Orofacial cleft" to identify eligible studies. We compiled the CADD score for all the mutations to determine the percentage of deleterious variants.

RESULTS

Twenty-one new mutations were identified from nine papers. The majority of these mutations were in exon 4. Mutations in exon 3 and 4 had CADD scores between 20 and 30 and mutations in exon 7-9 had CADD scores between 30 and 40. The presence of higher CADD scores in the protein-binding domain (exon 7-9) further confirms the crucial role played by this domain in the function of IRF6. In the new cases, we identified five IRF6 mutations, three novel missense mutations (p.Phe36Tyr, p.Lys109Thr, and p.Gln438Leu), and two previously reported nonsense mutations (p.Ser424*and p.Arg250*).

CONCLUSION

Mutations in the protein and DNA-binding domains of IRF6 ranked among the top 0.1% and 1% most deleterious genetic mutations, respectively. Overall, these findings expand the range of VWS mutations and are important for diagnostic and counseling purposes.

Van der Woude and Popliteal Pterygium Syndromes: Broad intrafamilial variability in a three generation family with mutation in IRF6

Patients with Van der Woude syndrome typically present with cleft lip, cleft lip and palate, or with cleft palate only. In contrast to non-syndromic cleft lip and/or palate, Van der Woude syndrome typically is characterized by bilateral, paramedian lower-lip pits. Popliteal pterygium syndrome shares features with Van der Woude syndrome, but, in addition, is characterized by a popliteal pterygium, genital anomalies, cutaneous syndactyly of the fingers and the toes, and a characteristic pyramidal fold of skin overlying the nail of the hallux. In some patients oral synechiae or eyelid synechiae are present. Van der Woude Syndrome and Popliteal pterygium syndrome are autosomal dominantly inherited disorders caused by heterozygous mutations in IRF6. We present a three generation family with tremendous intrafamilial phenotypic variability. The newborn index patient had a diagnosis of Popliteal pterygium syndrome. The mother presented with a classic Van der Woude Syndrome, while the maternal grandfather had Van der Woude Syndrome as well as minor signs of Popliteal pterygium syndrome. In all three affecteds the known pathogenic mutation c.265A>G, p.Lys89Glu in IRF6 was identified. While inter- as well as intra-familial variability has been described in IRF6-related disorders, the occurrence of a typical Van der Woude Syndrome without any other anomalies as well as a diagnosis of Popliteal pterygium syndrome in the same family is rare. © 2016 Wiley Periodicals, Inc.

A case of vander woude syndrome with rare phenotypic expressions

Van der Woude syndrome (VWS) is a rare developmental disorder with an autosomal dominant inheritance. The prevalence of VWS varies from 1:100,000 to 1:40,000 still born or live births. It has variable expressivity and generally expressed as orofacial manifestations like lower lip pits, cleft lip and/or cleft palate, hypodontia, cleft or bifid uvula, ankyloglossia and some extraoral anomalies involving hand, foot and genitalia. Thorough family history, clinical examination and genetic counseling helps in correct diagnosis of VWS as Popliteal pterygium syndrome has overlapping clinical manifestations. Most cases of Van der Woude syndrome have been associated with mutations and genetic changes. The current case has classical features of VWS with some rare features like undescended small testis and unreported finding of syndactyly of second and third toe adds on to the existing knowledge of VWS presentation.

Popliteal pterygium syndrome: a rare entity

The popliteal pterygium syndrome is a congenital malformation that includes orofacial, musculoskeletal and genitourinary anomalies. It is a rare autosomal dominant disorder. We report one family with popliteal pterygium syndrome affecting father and his two daughters, who underwent surgical corrections for multiple congenital malformations.

Treatment of popliteal pterygium using an Ilizarov external fixator

Popliteal pterygium syndrome is a rare congenital disorder that consists of popliteal webs and craniofacial, genitourinary and extremity anomalies. Only moderate successful surgical excision of the fibrotic band within the popliteal web has been reported because the nerves and vessels in the affected site are short and displaced into the web and they are attached to adjacent tissues. We performed hamstring tenotomy on the ischial tuberosity, tenotomy of the flexor hallucis longus and Z-lengthening of the Achilles tendon on the ankle in our patient, and this was followed by gradual correction using an Ilizarov external fixator. Full extension of the knee joint was achieved at the ninth postoperative week. However, some recurrence of flexion contracture was noted at two years follow-up. Gradual soft tissue lengthening with an Ilizarov external fixator can be one of the optimal procedures when excision of a fibrous band and Z-plasty are not possible due to severe adhesion of the nerves and vessels into a fibrotic band. However, a cautious approach is recommended when considering the high risk of recurrence.