An Update on Common Chromosome Microdeletion and Microduplication Syndromes

This review summarizes common microdeletion and microduplication syndromes and highlights important updates in patient-care needs for people with these conditions (22q11.2, 7q11.23, 17p11.2, and 16p11.2). These conditions are in chromosomal "hotspots" and have an estimated prevalence of 1 in 1,000 to 1 in 25,000. Some conditions have possible increased or decreased genetic risk of schizophrenia (22q11.2 deletion and duplication), or risk of aortic dilation (7q11.23 duplication) versus aortic stenosis (7q11.23 deletion). Many of these conditions are associated with developmental delay, autism, and/or multiple congenital anomalies and would not be detected with a karyotype. Chromosomal microarray analysis will detect all these conditions with a single screening test, allowing for the appropriate diagnosis and management of these patients. [Pediatr Ann. 2018;47(5):e198-e203.].

Novel agents in chronic lymphocytic leukemia

The advent of novel small-molecule inhibitors has transformed the treatment approaches for patients with chronic lymphocytic leukemia (CLL). These therapies are becoming increasingly used in patients with relapsed disease, patients with 17p deletion, and, as of recently, also in the frontline setting for previously untreated patients with CLL. Moreover, many of these are oral therapies that are significantly less myelosuppressive than chemoimmunotherapy. However, these agents have their own set of unique toxicities with which providers must gain familiarity. There is also ongoing development of second-generation agents which have the promise of less toxicity than the US Food and Drug Administration (FDA)-approved compounds. In addition, immunotherapy and the role of the microenvironment are becoming increasingly important and have therapeutic implications in the treatment of patients with CLL. Ultimately, investigators need to evaluate how to position these and other new exciting therapies and decide on the ultimate role for chemoimmunotherapy in modern times.

Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a mental retardation syndrome with distinctive behavioral characteristics, dysmorphic features, and congenital anomalies ascribed to an interstitial deletion of chromosome 17p11.2. Severe sleep disturbances and maladaptive daytime behavior have been linked to an abnormal circadian rhythm of melatonin with a diurnal instead of nocturnal secretion of this hormone. SMS provides a demonstration of a biological basis for sleep disorder in a genetic disease. Considering that clock genes mediate the generation of circadian rhythm, haploinsufficiency for a circadian system gene, mapping to chromosome 17p11.2, may cause the inversion of the melatonin circadian rhythm in SMS. The disorder of circadian timing in SMS may also affect entrainment pathway (retinohypothalamic tract), pacemaker functions (suprachiasmatic nuclei), or synthesis and release of melatonin by the pineal gland. Elucidating pathophysiological mechanisms of behavioral phenotypes in genetic disease can provide an original therapeutic approach in SMS: blockade of endogenous melatonin production during the day combined with exogenous melatonin administration in the evening.

Potocki-Lupski syndrome: a microduplication syndrome associated with oropharyngeal dysphagia and failure to thrive

OBJECTIVE

Failure to thrive (FTT) is a feature of children with Potocki-Lupski syndrome (PTLS) [duplication 17p11.2]. This study was designed to describe the growth characteristics of 24 subjects with PTLS from birth through age 5 years in conjunction with relevant physical features and swallow function studies.

STUDY DESIGN

We evaluated 24 individuals with PTLS who were ascertained by chromosome analysis and/or array comparative genome hybridization. Clinical assessments included review of medical records, physical examination, otolaryngological examination, and swallow function studies. Measures of height and weight were converted to Z-scores.

RESULTS

The mean weight-for-age and weight-for-length Z-scores at birth were lower (P < .01) than the reference standard and did not change with age. A history of poor feeding, hypotonia, and FTT were reported in 92%, 88%, and 71%, respectively. Individuals with hypotonia had lower weight-for-age and body mass index-for-age Z-scores (P = .01). Swallow function studies demonstrated at least one abnormality in all subjects.

CONCLUSIONS

FTT is common in children with PTLS. We hypothesize that oropharyngeal dysphagia and hypotonia likely contribute to FTT in patients with PTLS and recommend that once a diagnosis is established, the individual be assessed for feeding and growth issues and be availed of oromotor therapy and nutritional services.