Molecular analysis of KAL-1 in a series of Kallmann syndrome and normosmic idiopathic hypogonadotropic hypogonadism patients from Northwestern China

Prevalence and Phenotypic Effects of Copy Number Variants in Isolated Hypogonadotropic Hypogonadism

CONTEXT

The genetic architecture of isolated hypogonadotropic hypogonadism (IHH) has not been completely defined.

OBJECTIVE

To determine the role of copy number variants (CNVs) in IHH pathogenicity and define their phenotypic spectrum.

METHODS

Exome sequencing (ES) data in IHH probands (n = 1394) (Kallmann syndrome [IHH with anosmia; KS], n = 706; normosmic IHH [nIHH], n = 688) and family members (n = 1092) at the Reproductive Endocrine Unit and the Center for Genomic Medicine of Massachusetts General Hospital were analyzed for CNVs and single nucleotide variants (SNVs)/indels in 62 known IHH genes. IHH subjects without SNVs/indels in known genes were considered "unsolved." Phenotypes associated with CNVs were evaluated through review of patient medical records. A total of 29 CNVs in 13 genes were detected (overall IHH cohort prevalence: ~2%). Almost all (28/29) CNVs occurred in unsolved IHH cases. While some genes (eg, ANOS1 and FGFR1) frequently harbor both CNVs and SNVs/indels, the mutational spectrum of others (eg, CHD7) was restricted to SNVs/indels. Syndromic phenotypes were seen in 83% and 63% of IHH subjects with multigenic and single gene CNVs, respectively.

CONCLUSION

CNVs in known genes contribute to ~2% of IHH pathogenesis. Predictably, multigenic contiguous CNVs resulted in syndromic phenotypes. Syndromic phenotypes resulting from single gene CNVs validate pleiotropy of some IHH genes. Genome sequencing approaches are now needed to identify novel genes and/or other elusive variants (eg, noncoding/complex structural variants) that may explain the remaining missing etiology of IHH.

Correlation of Olfactory Phenotype by Indian Smell Identification Test and Quantitative MRI of Olfactory Apparatus in Idiopathic Hypogonadotropic Hypogonadism

OBJECTIVES

Idiopathic hypogonadotropic hypogonadism (IHH) can be associated with anosmia/hyposmia. The objective of this study is to evaluate olfaction by Indian smell identification test (INSIT) and measure olfactory bulbs (OBs) and sulci using dedicated magnetic resonance imaging (MRI) in patients with IHH and correlate MRI findings with INSIT.

METHODS

Forty patients with IHH underwent (a) brief smell identification test (INSIT) and (b) MRI of the olfactory apparatus. The size of olfactory sulcus and bulb was quantified and compared with the normative data obtained in 22 controls. The agreement between INSIT and MRI was assessed using Kappa index.

RESULTS

Of the 40 patients, 8 patients who reported abnormal smell sensation and 12 of the remaining 32 patients who reported normal smell sensation historically had a low score on INSIT. Thus, there were 20 patients with Kallmann syndrome (KS) and the rest 20 were normosmic IHH (nIHH). Of 40 patients with IHH, MRI finding was suggestive of normal (n = 16), hypoplastic (n = 12), and aplastic (n = 12) olfactory apparatus. All 20 patients with KS have olfactory abnormalities (n = 12 aplastic, n = 8 hypoplastic), and 4 of 20 nIHH have olfactory abnormalities (hypoplastic only) on MRI. There is (a) significant positive correlation (r = 0.54, P = 0.013) between the OB volume (MRI) and smell test scores and (b) moderate agreement (Kappa index: 0.49) between smell defect (INSIT score ≤ 4) and aplastic olfactory apparatus.

CONCLUSION

Self-reporting of smell significantly underestimates olfactory phenotype, and hence we recommend an objective smell test to differentiate KS from nIHH. Olfactory phenotype significantly correlates with MRI quantification of olfactory apparatus in IHH.

An objective olfactory evaluation and its correlation with magnetic resonance imaging findings in Asian Indian patients with idiopathic hypogonadotropic hypogonadism

OBJECTIVE

Idiopathic hypogonadotropic hypogonadism (IHH) can be associated with subnormal sense of smell. The objective of our study was to determine if there is a correlation between the olfactory phenotype (clinical smell test) of IHH patients and structural abnormalities in the olfactory apparatus on magnetic resonance imaging (MRI).

METHODS

This was a single-center prospective case control study. Forty-one IHH patients underwent a brief University of Pennsylvania Smell Identification Test (UPSIT) and an MRI of the olfactory apparatus. The size of the olfactory sulcus and bulb were quantified and compared with the normative data of 40 controls. Agreement between UPSIT and MRI results was assessed using the kappa index.

RESULTS

MRI showed that the olfactory apparatus was normal in 17 patients, hypoplastic in 14, and aplastic in 10. All 13 patients who complained of anosmia and 12 of 28 patients who reported normosmia had a low UPSIT score. Thus, 25 patients had Kallmann syndrome (KS) and 16 were normosmic IHH (nIHH). MRI revealed abnormalities in 68% of KS and 37.5% of nIHH patients. The MRI abnormalities in KS patients were aplasia (56%) and hypoplasia (44%). All 6 nIHH patients with abnormal MRI had hypoplasia. A significant positive correlation (r = 0.61; P<.01) between olfactory bulb volume (from MRI) and smell-test score was found, and there was good agreement (kappa index, 0.72) between anosmia and the presence of an aplastic olfactory apparatus.

CONCLUSION

Self-reporting of the sense of smell significantly underestimates olfactory phenotype; hence, we recommend an objective smell test to distinguish KS from nIHH. Olfactory phenotype correlates well with MRI quantification of the olfactory apparatus in IHH.

The KAL1 pVal610Ile mutation is a recessive mutation causing Kallmann syndrome

OBJECTIVE

To present the clinical, genetic, biochemical, and molecular findings in two Chinese siblings with X-linked recessive Kallmann syndrome (KS).

DESIGN

Case report.

SETTING

University medical center.

PATIENT(S)

Two Chinese siblings.

INTERVENTION(S)

Clinical evaluation, hormone assays, and gene mutation research.

MAIN OUTCOME MEASURE(S)

Endocrinologic evaluation and genetic analysis.

RESULT(S)

A missense mutation of KAL1, c.1828G>A, led to pVal610Ile substitution in two brothers with KS; their mother is heterozygous for this missense mutation encoded by single-nucleotide polymorphism rs2229013.

CONCLUSION(S)

Mutation analysis revealed that a missense mutation of KAL1 in two brothers with KS, while their mother was heterozygous for this missense mutation encoded by the single-nucleotide polymorphism rs2229013. Variant alleles of KAL1 related to X-linked recessive KS expand the spectrum of KAL1 mutations causing KS.

Clinical assessment and genomic landscape of a consanguineous family with three Kallmann syndrome descendants

Although some genes that cause Kallmann syndrome (KS) have been identified by traditional linkage analysis and candidate gene techniques, the syndrome's molecular etiology in the majority of patients remains poorly understood. In this paper, we present the clinical assessments of a consanguineous Han Chinese family with three KS descendants. To understand the molecular etiology of KS from a genome-wide perspective, we investigated the genome-wide profile of structural variation in this family using the Affymetrix Genome-Wide Human SNP Array 6.0 platform. The results revealed that the three affected individuals had common copy number variants (microdeletions) on chromosomes 1p21.1, 2q32.2, 8q21.13, 14q21.2 and Xp22.31. Moreover, the copy number variants on Xp22.31 were located in the intron of KAL1, which causes X-linked KS. Two PCR assays were performed on these regions to validate the results obtained using the chips. In addition, genomic microdeletions in this region were verified in one of 29 Han Chinese sporadic KS cases and one of four other family cases, but not in 26 Han Chinese sporadic normosmic idiopathic hypogonadotropic hypogonadism cases and 100 unrelated Han Chinese normal controls. Our results provide a novel insight into the relative contributions of certain copy number variants to KS's molecular etiology and generate a list of interesting candidate regions for further studies.