PPP1R12A-Related Urogenital and/or Brain Malformation Syndrome

Excerpt

Clinical characteristics: Individuals with PPP1R12A-related urogenital and/or brain malformation syndrome (UBMS) usually present with multiple congenital anomalies, commonly including brain and/or urogenital malformations. The brain abnormalities are variable, with the most severe belonging to the holoprosencephaly spectrum and associated with moderate-to-profound intellectual disability, seizures, and feeding difficulties. In individuals without brain involvement, variable degrees of developmental delay and/or intellectual disability may be present, although normal intelligence has been seen in a minority of affected individuals. Eye abnormalities and skeletal issues (kyphoscoliosis, joint contractures) can also be present in individuals of either sex. Regardless of the presence of a brain malformation, affected individuals with a 46,XY chromosome complement may have a disorder of sex development (DSD) with gonadal abnormalities (dysgenetic gonads or streak gonads). Individuals with a 46,XX chromosome complement may have varying degrees of virilization (clitoral hypertrophy, posterior labial fusion, urogenital sinus).

Diagnosis/testing: The diagnosis of PPP1R12A-related UBMS is established in a proband with suggestive findings and a heterozygous pathogenic variant in PPP1R12A identified by molecular genetic testing.

Management: Treatment of manifestations. Gonadectomy should be considered in those with dysgenetic gonads; referral of 46,XY undervirilized males to a urologist for consideration of surgical correction of hypospadias and cryptorchidism; referral of 46,XX virilized females to a urologist and/or adolescent OB/GYN for surgical treatment of urogenital sinus; referral to endocrinologist for treatment of hormonal issues at and after puberty for those with gonadal abnormalities; referral to psychologist or multidisciplinary DSD clinic, if available. Treatment of feeding difficulties including consideration of gastrostomy tube placement for those with persistent feeding issues or failure to thrive; standard treatment for renal anomalies, epilepsy, developmental delay/intellectual disability, constipation, bowel atresia, hearing impairment, vision abnormalities/strabismus, kyphoscoliosis, and joint contractures, as needed.

Surveillance. Regular follow up by an interdisciplinary DSD team (if available) including endocrinology, genetics, obstetrics/gynecology, psychology, and urology for those who had DSD as part of their features. Measurement of growth parameters, evaluation of nutritional status and safety of oral intake, assessment for constipation, monitoring of developmental progress and educational needs, monitoring for changes in seizures, and assessment for new neurologic manifestations at each visit; monitoring for timing and progression of puberty at each visit starting in late childhood through adolescence; assessment for scoliosis or kyphosis at each visit until growth is complete; ophthalmology and audiology evaluations annually or as clinically indicated.

Genetic counseling: PPP1R12A-related UBMS is an autosomal dominant disorder typically caused by a de novo pathogenic variant. If the PPP1R12A pathogenic variant identified in the proband cannot be detected in the leukocyte DNA of either parent, the recurrence risk to sibs is estimated to be 1% because of the theoretic possibility of parental germline mosaicism. Once the PPP1R12A pathogenic variant has been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible.