Congenital hemihypertrophy with hemihypertrichosis

Post-zygotic ACTB mutations underlie congenital smooth muscle hamartomas

BACKGROUND

Congenital smooth muscle hamartomas (CSMHs) are benign lesions that share clinical and histopathological features with Becker nevus, a mosaic disorder associated with post-zygotic ACTB mutations. Given the clinical and histopathological overlap between CSMH and Becker nevus, we hypothesized that post-zygotic mutations in ACTB may underlie CSMH.

METHODS

Direct sequencing of ACTB gene in affected and unaffected tissue isolated from one case of hemihypertrichosis and hemihypertrophy corresponding to giant segmental CSMH and hemihypertrophy. This was followed by direct sequencing with and without enrichment assay for hotspot ACTB mutations in affected tissue from 12 samples of isolated CSMH from unrelated individuals.

RESULTS

In total we identified somatic missense ACTB mutations in 9 out of 13 CSMHs (69%). Mutations were either novel or previously reported in Becker nevi and Becker nevus syndrome.

CONCLUSIONS

CSMHs result from post-zygotic ACTB mutations. This study proves that CSMHs and Becker nevi are nosologically related, and expand the phenotypic spectrum of ACTB mutations.

Hypertrichotic patches as a mosaic manifestation of Proteus syndrome

BACKGROUND

Proteus syndrome is an overgrowth disorder caused by a mosaic activating AKT1 variant. Hair abnormalities in Proteus syndrome have rarely been reported, and frequencies of such findings have not been elucidated.

OBJECTIVE

To define the types and frequencies of hair findings in individuals with Proteus syndrome.

METHODS

A cross-sectional study was conducted of individuals with clinical features of Proteus syndrome and a confirmed pathogenic variant in AKT1 evaluated between November 1996 and June 2019 at the National Institutes of Health Clinical Center. Medical records were reviewed for patterning, density, and color of hair on the body and scalp.

RESULTS

Of 45 individuals evaluated, 29 (64%) had asymmetric hypertrichosis on the body. This included unilateral blaschkoid hypertrichotic patches overlying normal skin or epidermal nevi in 16 (36%), unilateral nonblaschkoid hypertrichotic patches in 11 (24%), and unilateral limb hypertrichosis in 10 (22%). Diffuse, scattered, or patchy changes in scalp hair density or color were present in 11 individuals (24%).

LIMITATIONS

The retrospective, observational design, and limited longitudinal follow-up.

CONCLUSIONS

Asymmetric variations in hair distribution, thickness, length, and color contribute to the overall mosaic appearance of the skin in Proteus syndrome, an observation that provides novel insights into the role of phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling in skin appendage development.

Hemihyperplasia: History of medicine assists medical genetics

This paper examines the role of the history of medicine in case of congenital isolated hemihyperplasia. Isolated hemihyperplasia is a genetic disorder in which one side of the body grows more than the other, causing visible lateral asymmetry of the human body. The date of the occurrence of the genetic mutation that leads to hemihyperplasia is not known yet. The aim of the current research was to confirm or to disprove the fact that isolated hemihyperplasia was first described in the first half of the 19th century. Using the case of hemihyperplasia we aimed to demonstrate how historical analysis may assist medical genetics in cases when estimating a mutation date is necessary. Medical literature from 1573 onwards was searched for any mention of hemihypertrophy, hemihyperplasia, hemi-gigantism, partial gigantism, hemi-macrosomia and other possible descriptions for pathological lateral body overgrowth. Historical analysis suggests that the mutation in question occurred in the first half of the 19th century, approximately 200 years ago. This led to the appearance of hemihyperplasia and subsequent hemihyperplasia-including syndromes. An additional genetic research is needed for investigation of the development of the involved chromosomal region instability since this period. Such research may use the timeline orientation provided by the history of medicine.

Idiopathic corporeal hemihypertrophy associated with hemihypertrichosis

The hemihypertrophy or hemihyperplasy is a rare congenital abnormality, characterized by an asymmetric growth of the limbs, the trunk, and the face or half of the entire body. It may be isolated or be part of several syndromes including Beckwith-Wiedemann syndrome, Klippel-Trenaunay-Weber syndrome, Silver-Russell syndrome and Proteus syndrome. In its isolated form, it is called idiopathic. The latter may be associated with several anomalies including dermatological and urogenital abnormalities with increased risk of developing embryonal tumors. We report the case of a 22-month-old infant, who was referred by his pediatrician at the age of 15 months for a corporeal hemihypertrophy associated with hemihypertrichosis. In his medical history, a second degree parental consanguinity and a hypospadias in the father and a paternal uncle were found. Clinical examination found a weight and a size greater than chronological age (3 standard deviations), a hemihypertrophy of entire left side with a difference of length and diameter between the left and right limbs of 2 cm. The hemihypertrichosis was widespread in the left body and the genital examination found a hypospadias. Biological and radiological assessments did not show any abnormality, with the exception of an initially high plasma testosterone level, which gradually normalized. Thus, the diagnosis of idiopathic hemihypertrophy with congenital hemihypertrichosis was retained. This is the fourth case reported in the literature. Its management is similar to all hemihypertrophies, which consists of an initial assessment to detect an embryonic tumor, followed by a monitoring protocol including an abdominal and renal ultrasound every 6 months until the age of 8, determination of alpha-feto-protein every 6 to 12 weeks until the age of 4 years to track the development of the two most frequent tumors: Wilms tumor and hepatoblastoma. The hemihypertrophy associated with hemihypertrichosis has been exceptionally reported and the cause of this association has not been identified to date.