A patient with van Maldergem syndrome with endocrine abnormalities, hypogonadotropic hypogonadism, and breast aplasia/hypoplasia

Requirement of FAT and DCHS protocadherins during hypothalamic-pituitary development

Pituitary developmental defects lead to partial or complete hormone deficiency and significant health problems. The majority of cases are sporadic and of unknown cause. We screened 28 patients with pituitary stalk interruption syndrome (PSIS) for mutations in the FAT/DCHS family of protocadherins that have high functional redundancy. We identified seven variants, four of which putatively damaging, in FAT2 and DCHS2 in six patients with pituitary developmental defects recruited through a cohort of patients with mostly ectopic posterior pituitary gland and/or pituitary stalk interruption. All patients had growth hormone deficiency and two presented with multiple hormone deficiencies and small glands. FAT2 and DCHS2 were strongly expressed in the mesenchyme surrounding the normal developing human pituitary. We analyzed Dchs2-/- mouse mutants and identified anterior pituitary hypoplasia and partially penetrant infundibular defects. Overlapping infundibular abnormalities and distinct anterior pituitary morphogenesis defects were observed in Fat4-/- and Dchs1-/- mouse mutants but all animal models displayed normal commitment to the anterior pituitary cell type. Together our data implicate FAT/DCHS protocadherins in normal hypothalamic-pituitary development and identify FAT2 and DCHS2 as candidates underlying pituitary gland developmental defects such as ectopic pituitary gland and/or pituitary stalk interruption.

Coexistence of genetic conditions: exploring a possible relationship

We report on a 3-year-old boy who has congenital adrenal hyperplasia and a suspected Van Maldergem syndrome, another genetic condition, with the classic phenotype seen in our patient. The latter diagnosis was supported by a genetic test that showed a novel and likely pathogenic variant in a previously described gene of the syndrome. Paediatricians do encounter such a challenge of coexisting genetic conditions albeit infrequently, and advanced genetic analysis, example whole exome sequencing, increasingly report variants of unknown significance with a variable degree of potential pathogenicity. The treating physician needs to follow a systematic approach and entertain thorough literature search and brainstorming in order to prove or disprove any possible relationship between coexisting genetic conditions. The first step should be confirming the existence of the two conditions in the first place. In addition, when family segregation is unable to confidently make a sensible conclusion in such cases, a clinician should proceed to advanced functional studies to confirm pathogenicity. Then, one can explore further any hidden relationship between coexisting and possibly clinically-related genetic conditions.

Developmental disorders and malformations of the breast

Developmental abnormalities and malformations of the breast are rare and encompass a variety of genetic, syndromic, acquired and sporadic conditions. Abnormalities in development may include irregularities in the nipple areolar complex and/or the underlying glandular tissue, resulting in under or overdevelopment of breasts. Age of presentation and clinical severity is dependent on the underlying biologic cause. Abnormalities may involve the entirety of unilateral or bilateral breasts, particularly in association with syndromic conditions or endocrine abnormalities. Disordered development may also be focal, resulting in tumor-like lesions such as hamartomas, pseudoangiomatous stromal hyperplasia and gynecomastia. In this review, we discuss the disorders of breast development including etiologies, clinical presentations and corresponding histopathologic features.