Hypoparathyroidism-retardation-dysmorphism syndrome-Clinical insights from a large longitudinal cohort in a single medical center

Expanding the Phenotypic Spectrum of Kenny-Caffey Syndrome

CONTEXT

Kenny-Caffey syndrome (KCS) is a rare hereditary disorder characterized by short stature, hypoparathyroidism, and electrolyte disturbances. KCS1 and KCS2 are caused by pathogenic variants in TBCE and FAM111A, respectively. Clinically the phenotypes are difficult to distinguish.

OBJECTIVE

The objective was to determine and expand the phenotypic spectrum of KCS1 and KCS2 in order to anticipate complications that may arise in these disorders.

METHODS

We clinically and genetically analyzed 10 KCS2 patients from 7 families. Because we found unusual phenotypes in our cohort, we performed a systematic review of genetically confirmed KCS cases using PubMed and Scopus. Evaluation by 3 researchers led to the inclusion of 26 papers for KCS1 and 16 for KCS2, totaling 205 patients. Data were extracted following the Cochrane guidelines and assessed by 2 independent researchers.

RESULTS

Several patients in our KCS2 cohort presented with intellectual disability (3/10) and chronic kidney disease (6/10), which are not considered common findings in KCS2. Systematic review of all reported KCS cases showed that the phenotypes of KCS1 and KCS2 overlap for postnatal growth retardation (KCS1: 52/52, KCS2: 23/23), low parathyroid hormone levels (121/121, 16/20), electrolyte disturbances (139/139, 24/27), dental abnormalities (47/50, 15/16), ocular abnormalities (57/60, 22/23), and seizures/spasms (103/115, 13/16). Symptoms more prevalent in KCS1 included intellectual disability (74/80, 5/24), whereas in KCS2 bone cortical thickening (1/18, 16/20) and medullary stenosis (7/46, 27/28) were more common.

CONCLUSION

Our case series established chronic kidney disease as a new feature of KCS2. In the literature, we found substantial overlap in the phenotypic spectra of KCS1 and KCS2, but identified intellectual disability and the abnormal bone phenotype as the most distinguishing features.

Hypoparathyroidism-Retardation-Dysmorphism Syndrome due to a Variant in the Tubulin-Specific Chaperone E Gene as a Cause of Combined Immune Deficiency

BACKGROUND

Hypoparathyroidism-retardation-dysmorphism (HRD) syndrome is a disease composed of hypoparathyroidism, growth retardation, severe developmental delay, and typical dysmorphic features caused by the tubulin-specific chaperone E gene variant. Many patients succumb in infancy to HRD due to overwhelming infections mainly caused by Pneumococcus spp. Knowledge related to the immune system in these patients is scarce.

PURPOSE

To define the immune phenotype of a cohort of HRD patients including their cellular, humoral, and neutrophil functions.

METHODS

The study included HRD patients followed at Soroka University Medical Center. Clinical and immunological data were obtained, including immunoglobulin concentrations, specific antibody titers, lymphocyte subpopulations, lymphocyte proliferation, and neutrophil functions.

RESULTS

Nine patients (5 females and 4 males) were enrolled, aged 6 months to 15 years. All received amoxicillin prophylaxis as part of a routine established previously. Three patients had bacteremia with Klebsiella, Shigella spp., and Candida. Three patients had confirmed coronavirus disease 19 (COVID-19), and two of them died from this infection. All patients had normal blood counts. Patients showed high total IgA and IgE levels, low anti-pneumococcal antibodies in spite of a routine vaccination schedule, and reduced frequency of naive B cells with increased frequency of CD21lowCD27- B cells. All patients had abnormal T-cell population distributions, including reduced terminally differentiated effector memory CD8, inverted CD4/CD8 ratios, and impaired phytohemagglutinin (PHA)-induced lymphocyte proliferation. Neutrophil superoxide production and chemotaxis were normal in all patients tested.

CONCLUSION

HRD is a combined immunodeficiency disease with syndromic features, manifesting in severe invasive bacterial and viral infections.