Allison L. Goetsch

Characterisation of mutations of the phosphoinositide-3-kinase regulatory subunit, PIK3R2, in perisylvian polymicrogyria: a next-generation sequencing study

SUMMARY Background Bilateral perisylvian polymicrogyria (BPP), the most common form of regional polymicrogyria, causes the congenital bilateral perisylvian syndrome, featuring oromotor dysfunction, cognitive impairment and epilepsy. BPP is etiologically heterogeneous, but only a few genetic causes have been reported. The aim of this study was to identify additional genetic etiologies of BPP and delineate their frequency in this patient population. Methods We performed child-parent (trio)-based whole exome sequencing (WES) on eight children with BPP. Following the identification of mosaic PIK3R2 mutations in two of these eight children, we performed targeted screening of PIK3R2 in a cohort of 118 children with BPP who were ascertained from 1980 until 2015 using two methods. First, we performed targeted sequencing of the entire PIK3R2 gene by single molecule molecular inversion probes (smMIPs) on 38 patients with BPP with normal-large head size. Second, we performed amplicon sequencing of the recurrent PIK3R2 mutation (p.Gly373Arg) on 80 children with various types of polymicrogyria including BPP. One additional patient underwent clinical WES independently, and was included in this study given the phenotypic similarity to our cohort. All patients included in this study were children (< 18 years of age) with polymicrogyria enrolled in our research program. Findings Using WES, we identified a mosaic mutation (p.Gly373Arg) in the regulatory subunit of the PI3K-AKT-MTOR pathway, PIK3R2, in two children with BPP. Of the 38 patients with BPP and normal-large head size who underwent targeted next generation sequencing by smMIPs, we identified constitutional and mosaic PIK3R2 mutations in 17 additional children. In parallel, one patient was found to have the recurrent PIK3R2 mutation by clinical WES. Seven patients had BPP alone, and 13 had BPP in association with features of the megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH). Nineteen patients had the same mutation (Gly373Arg), and one had a nearby missense mutation (p.Lys376Glu). Across the entire cohort, mutations were constitutional in 12 and mosaic in eight patients. Among mosaic patients, we observed substantial variation in alternate (mutant) allele levels ranging from 2·5% (10/377) to 36·7% (39/106) of reads, equivalent to 5–73·4% of cells analyzed. Levels of mosaicism varied from undetectable to 17·1% (37/216) of reads in blood-derived compared to 29·4% (2030/6889) to 43·3% (275/634) in saliva-derived DNA. Interpretation Constitutional and mosaic mutations in the PIK3R2 gene are associated with a spectrum of developmental brain disorders ranging from BPP with a normal head size to the megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome. The phenotypic variability and low-level mosaicism challenging conventional molecular methods have important implications for genetic testing and counseling.

Genetic Counselors: Bridging the Oncofertility Information Gap

The oncofertility information gap is caused by insufficient patient education on the effects of cancer treatment on fertility and the option of fertility preservation. Many cancer patients do not recall ever discussing the impact of cancer treatment on fertility with their oncologist; because of this, multidisciplinary care that includes fertility treatment is especially valuable for bridging the information gap. Genetic counselors—who are specifically trained to deliver options and facilitate decision making while also focusing on psychosocial issues—are an untapped resource for educating cancer patients about fertility impairment and fertility preservation options. Genetic counselors use a nondirective counseling approach to facilitate a shared decision-making process with patients. Additionally, genetic counselors provide emotional support and can assess when to make a mental health referral. Genetic counselors believe that fertility preservation discussions are important and a part of the genetic counselor role, yet the majority of cancer genetic counselors are not discussing fertility preservation or referring patients, often because of the timing of cancer treatment. A majority (79.7 %) of genetic counselors have reported that the number one barrier to discussing fertility preservation is seeing a patient after they have already undergone cancer treatment. If healthcare providers refer individuals who have a personal or family history suggestive of a hereditary or familial cancer prior to cancer treatment or prophylactic surgery, genetic counselors would have an opportunity to discuss fertility preservation with patients, thereby effectively bridging the oncofertility information gap.

Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects almost 15% of women of reproductive age. As this disease is a syndrome, it affects different aspects of women health; it is much more prevalent in obese patients and affects different body systems leading to reproductive and metabolic complications. This chapter reviews different aspects of the disease, epidemiology, effect on menstrual cycle, hormonal implications, clinical manifestations, ultrasound findings, treatment options, and the effect on fertility. The goal is that all kind of physicians will achieve basic knowledge and will be able to diagnose this disease and derivate these patients to gynecologist and endocrinologist for correct treatment.

Nonmalignant Hematologic Diseases

When we think about hematologic diseases, it is easier to think of malignant conditions. However, there are several nonmalignant hematologic conditions that may have a huge impact on patient’s quality of life. These patients need to receive an appropriate treatment, and starting treatment early is crucial for them to have a good life. This chapter reviews nonmalignant hematologic conditions in which the curative treatment has a negative impact on fertility: major thalassemia, sickle disease, and aplastic anemia. The goal of this chapter is to give general information about these diseases, clinical manifestations, diagnosis, and treatment and fertility preservation options in case if needed.

Autoimmune Diseases: Rheumatic Diseases

There are more than 100 rheumatic diseases, including degenerative, inflammatory, and autoimmune diseases. These diseases have a major impact on the patient’s quality of life. Patients may have several limitations, and they depend on having a good response to the treatment they need. Normally, these diseases are diagnosed in young patients, and because of the disease and the treatment, they may have their reproductive capacity affected. This chapter reviews frequent rheumatic diseases, their epidemiology, physiopathology, clinical manifestations, treatment, and effect on fertility.

Options for Preserving Fertility

Significant improvements in medical treatments have led to decreased morbidity and mortality among individuals with complex medical conditions. These individuals are living longer, fuller lives. Advances in reproductive medicine now allow individuals with complex medical conditions whose disease or its treatment may impair fertility, to undergo fertility preservation. Fertility preservation options are available for females and males of prepubertal and reproductive age. This chapter provides a brief overview of clinically and experimentally available fertility preservation and restoration options, as well as future directions. Topics include semen cryopreservation, gonadal shielding, testicular tissue cryopreservation, embryo cryopreservation, oocyte cryopreservation, ovarian tissue cryopreservation, and ovarian suppression.

Disorders of the Sex Chromosomes and Sexual Development

Sexual development is driven by a number of genetic factors, many of which are associated with the sex chromosomes. Typically, males have one X chromosome and one Y chromosome, while females have two X chromosomes. Differences in the number of sex chromosomes or pathogenic variants in genes involved in sex development often lead to differences in multiple body systems. Individuals with sex chromosome abnormalities and disorders of sexual development may be candidates for fertility preservation and discussion of genetic risk for future offspring. This chapter discusses gonadal function, fertility potential and preservation, and reproductive considerations for individuals with these disorders.

Premature Ovarian Insufficiency

Premature ovarian insufficiency is a multicausal non-frequent disease (1%) that has a high impact on women health; not only because it impairs fertility but it also has huge effects on global health due to hypoestrogenism, osteoporosis, and cardiovascular risks. We analyze different etiologies; idiopathic, genetic, autoimmune, and iatrogenic; and treatment options.

Autoimmune Diseases: Myasthenia Gravis and Multiple Sclerosis

Myasthenia gravis and multiple sclerosis are both autoimmune diseases that affect the neuromuscular system. Patients affected by these two diseases are frequently women younger than 40 years old. Multiple sclerosis has a relapsing and remitting course, but both diseases course with progressive deterioration. Their effect on fertility has to do more with their effect on self-esteem, sexuality, and the therapies these patients require. This chapter reviews the physiopathology of these diseases, the effect of their treatments, and effect on fertility.

Digestive Autoimmune Diseases: Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) affect especially young patients in reproductive age. IBDs consist in a group of chronic inflammatory conditions that mainly affect the colon and the small intestine. The most frequent IBDs are Crohn’s disease and ulcerous colitis (UC) disease. IBDs significantly affect several reproductive aspects, not only fertility but sexual function. The goal of this chapter is to offer readers a detailed description of these two diseases from prevalence and etiology to clinical manifestations diagnosis and treatment and the effect of both diseases on the reproductive function.